New Jersey Form ST-51 is the Monthly Remittance Statement of Sales and Use Tax that every registered New Jersey seller must file and pay through the New Jersey Division of Taxation online portal whenever the sales tax collected for the first or second month of a calendar quarter exceeds $500. The form acts as a prepayment, not a final return, because the quarterly Form ST-50 reconciles the full three-month period. Filing late or skipping a month even when you owe the tax triggers a 5% late-filing penalty, a separate 5% late-payment penalty, and interest at the prime rate plus 3%, which compounds fast for small retailers.
The current ST-51 is filed exclusively through the state’s Sales and Use Tax Online Filing system, and the New Jersey Division of Taxation reports that more than 320,000 active sales tax accounts file ST-50 and ST-51 returns each year, with rejection or correction rates hovering near 8% due to wrong period-ending dates, misclassified gross receipts, and missed thresholds.
Here is what you will learn in this guide:
- 📋 Exactly which months require ST-51 and which do not, with the $500 threshold rule explained in plain English, including how seasonal businesses handle slow months
- 🧮 A line-by-line walkthrough of every field on the New Jersey ST-51 form, including the taxpayer ID, period ending date, gross receipts, deductions, taxable sales, and amount due
- 👥 Three full named-filer scenarios — a small retailer, a busy restaurant, and a UEZ-certified shop — showing the entered values
- 💳 Every filing channel allowed under N.J.A.C. 18:24, including the online portal, ACH debit, ACH credit, e-check, and credit card with fees
- ⚠️ The ten most common ST-51 mistakes, the consequences each one triggers, and the do’s, don’ts, pros, cons, and twelve answered FAQs covering field-level confusion
What the Form Is and Who Must File It
New Jersey Form ST-51 is a monthly remittance statement required under the New Jersey Sales and Use Tax Act, N.J.S.A. 54:32B. It is not a stand-alone return. It is a prepayment of the sales tax you collected during the first or second month of a calendar quarter. The third month of every quarter is always reported on Form ST-50, the quarterly return, which reconciles the entire three-month period.
You must file ST-51 only when two conditions are both true. First, your business collected more than $500 in New Jersey sales and use tax during the month. Second, the month is the first or second month of a calendar quarter — January, February, April, May, July, August, October, or November. If you collected $500 or less in a given first or second month, you skip ST-51 entirely and report that month’s tax on the next ST-50.
The filer is almost always the business owner, the in-house bookkeeper, or an outside CPA acting under a power of attorney filed on Form M-5008-R. Sole proprietors, single-member LLCs, partnerships, S-corporations, and C-corporations all use the same ST-51 if they hold a New Jersey Certificate of Authority. Out-of-state remote sellers that crossed the economic nexus thresholds of $100,000 in gross revenue or 200 separate transactions into New Jersey must also file.
Failure to file when required exposes the business to a 5% late-filing penalty per month up to 25%, plus a 5% late-payment penalty, plus interest at the prime rate plus 3 percentage points, all compounding under the rules in N.J.S.A. 54:49-4. The Division of Taxation can also revoke the Certificate of Authority for repeat non-filers, which legally bars the business from making taxable sales in New Jersey.
Before You Start: Documents and Information You Need
Before you log into the Sales and Use Tax Online Filing portal, gather every piece of data below. Missing any one item forces you to abandon the session, since the portal times out after 20 minutes of inactivity. Filers who prepare these items in advance complete ST-51 in under ten minutes.
- New Jersey Taxpayer Identification Number (12 digits). This is the number printed on your Certificate of Authority. Without it, the portal cannot match your business record, and the system will reject the login.
- PIN or myNewJersey login credentials. New filers must register a myNewJersey ID and link it to their Premier Business Services account. Lost PINs are recovered through the Premier Business Services password reset, but the recovery letter is mailed and can take 7 to 10 business days.
- Federal Employer Identification Number (FEIN) or Social Security Number. Used as a backup match when the NJ ID is rejected. A mismatch with IRS records flags the account for manual review.
- Gross receipts for the month, broken out by taxable and exempt sales. Pull this from your point-of-sale or accounting system. Misstating gross receipts is the single most common ST-51 error.
- Total New Jersey sales tax collected during the month. This is the actual dollar amount your registers, invoices, or POS reports collected at 6.625%, the current rate confirmed by the NJ Division of Taxation rate notice.
- Use tax accrued on out-of-state purchases. If you bought taxable property or services from a vendor that did not charge NJ sales tax and you used those items in New Jersey, you owe use tax at 6.625%.
- UEZ-certified sales (if applicable). Urban Enterprise Zone businesses certified under N.J.S.A. 52:27H-79 collect tax at 3.3125% on qualifying retail sales and must track those sales separately.
- Bank routing and account number for ACH debit. Required because ST-51 must be paid at the time of filing. The portal will not accept a return without payment.
- Prior period adjustments or credit memos. If you over-collected last month and refunded a customer, document it. The portal does not allow negative line entries without backup notes.
- Confirmation number storage plan. Decide where you will save the confirmation number the portal issues — many filers lose this number, which is the only proof of timely filing if the Division questions the submission.
Where to Get the Form and How to Access It
You will not download a paper ST-51, fill it in by hand, and mail it. New Jersey mandates electronic filing for all ST-51 and ST-50 returns under N.J.A.C. 18:2-2, and paper submissions are returned unprocessed. The blank reference copy is posted at the official ST-51 PDF so filers can preview the fields, but the actual filing happens online.
There are two approved electronic channels. The first is the Sales and Use Tax Online Filing web application, which is the most common path. The second is the telephone filing system at 1-877-829-2866, which uses voice prompts and a touch-tone keypad for filers without internet access. Both channels require the 12-digit NJ Taxpayer ID and the four-digit PIN.
The portal works in any current browser. Internet Explorer 11 still loads the system, but the Division of Taxation recommends Chrome, Edge, Firefox, or Safari. Mobile browsers work, but the screen layout truncates the deduction worksheet, so a desktop or laptop is preferred. Sessions time out after 20 minutes of inactivity, and there is no autosave, so prepare your numbers before logging in.
If you are a new business, register first through the NJ Business Registration application (NJ-REG) to receive your Certificate of Authority and Taxpayer ID. The state mails the certificate within 7 to 14 days, and the PIN follows in a separate letter. Without both items, you cannot file ST-51, and any tax collected during the waiting period must still be remitted on the first ST-50 after registration.
Step-by-Step: How to Fill Out New Jersey Form ST-51 Line by Line
The ST-51 has a small number of fields compared to most state tax forms, but each one carries weight. Walk through them in order, exactly as the Sales and Use Tax Online Filing portal presents them. Every field below gets its own H3 with plain-English instructions, an example entry in italics, a nuance, the most common mistake and consequence, and the misconception filers carry into the box.
Field 1: New Jersey Taxpayer Identification Number
Plain English. This is the 12-digit number the state assigned to your business when you registered. The portal asks for it on the very first login screen.
How to answer it. Type the full 12 digits with no dashes, no spaces, and no letters. The first nine digits usually match your FEIN. The last three are the location suffix.
Example entry. Maria Lopez, owner of Lopez Boutique LLC, enters 123456789000 in the Taxpayer ID box.
Nuance. If your business has more than one location, each location has its own three-digit suffix. Use the suffix tied to the location that made the sales for the month. Filing under the wrong suffix routes the payment to the wrong location’s account.
Common mistake and consequence. Filers often paste their FEIN with dashes (12-3456789) and stop at nine digits. The portal rejects the login, and after three failed attempts the account locks for 24 hours, which can push a filer past the 20th-of-the-month deadline.
Misconception. Many filers think the Taxpayer ID and the FEIN are interchangeable. They are not. The NJ Taxpayer ID is FEIN plus location suffix, and the portal will not accept the FEIN alone.
Field 2: PIN
Plain English. The PIN is the four-digit security code the Division of Taxation mailed you when your Certificate of Authority was issued.
How to answer it. Type the four digits as they appear on the PIN letter. Do not guess. After three wrong PINs, the account locks.
Example entry. Marcus Bell, owner of Bell’s Auto Detailing, enters 4827 in the PIN field.
Nuance. If you lost the PIN letter, request a reset through Premier Business Services. The reset letter is mailed, not emailed, so order it at least two weeks before a filing deadline.
Common mistake and consequence. Filers confuse the PIN with the myNewJersey password. The PIN is a separate four-digit number tied to the tax account. Entering the myNewJersey password locks the account and requires a written reset request.
Misconception. Some filers believe the PIN expires every year. It does not. The same PIN stays active until the business closes the account or the Division of Taxation reissues one after a security event.
Field 3: Period Ending Date
Plain English. This box asks which month you are paying tax for. Enter the last day of that month.
How to answer it. Use MM/DD/YYYY format. The portal pre-populates a dropdown, so pick the correct month and year from the list.
Example entry. For the January 2026 filing due February 20, 2026, Aisha Patel enters 01/31/2026.
Nuance. ST-51 only covers the first or second month of a quarter. If you select March, June, September, or December, the portal blocks the filing and redirects you to ST-50, the quarterly return.
Common mistake and consequence. Filers select the month they are filing in (February) instead of the month the tax was collected (January). This misallocates the payment to the wrong period and triggers a Notice of Deficiency for the actual unpaid month, with penalties and interest accruing until the misposted payment is moved.
Misconception. Filers think a payment posted to the wrong month “fixes itself” at quarter-end on ST-50. It does not. The Division of Taxation flags both months — the unpaid one and the overpaid one — and the filer must call to request a manual transfer.
Field 4: Gross Receipts for the Month
Plain English. This is every dollar your business took in for sales of tangible personal property and taxable services during the month, before any deductions.
How to answer it. Enter the total in dollars and cents, no commas, no dollar sign. Pull the figure from your POS sales report or general ledger.
Example entry. Lopez Boutique had January gross receipts of $42,318.55, so Maria enters 42318.55.
Nuance. Gross receipts include cash, check, credit card, and gift card redemptions. They do not include sales tax collected, customer deposits on layaway items not yet delivered, or returns from prior periods. Including the sales tax in gross receipts inflates the number and creates a reconciliation gap on ST-50.
Common mistake and consequence. Filers report net sales (after returns and discounts) in this box and then deduct returns again on the deductions worksheet. Double-counting the deduction understates taxable sales, and the Division of Taxation flags the mismatch through its audit selection program.
Misconception. Filers assume gross receipts means “money I kept.” It means total sales revenue, including amounts later refunded. Refunds belong on the deductions line, not as a reduction of gross receipts.
Field 5: Deductions
Plain English. This line lets you subtract the portion of gross receipts that is not subject to New Jersey sales tax.
How to answer it. Add up resale sales (with valid ST-3 resale certificates), exempt-use sales (Form ST-4), sales of exempt food and clothing, and sales delivered out of state. Enter the total in dollars and cents.
Example entry. Bell’s Auto Detailing sold $1,200 of detailing services to a fleet customer with a valid ST-4. Marcus enters 1200.00 on the deductions line.
Nuance. You must keep the signed exemption certificate on file for four years under N.J.A.C. 18:24-10.4. If a Division auditor asks for the certificate and you cannot produce it, the deduction is disallowed and the tax is assessed.
Common mistake and consequence. Filers deduct exempt sales without first collecting the exemption certificate. On audit, the Division reverses the deduction, assesses 6.625% tax on the full amount, and adds penalty and interest.
Misconception. Filers think a verbal claim of “I’m tax-exempt” from a customer is enough. It is not. New Jersey requires a fully completed, signed exemption certificate before the sale closes.
Field 6: Taxable Receipts
Plain English. This is gross receipts minus deductions. It is the dollar amount of sales that are actually subject to the 6.625% rate.
How to answer it. The online portal calculates this automatically once you enter Fields 4 and 5. Verify the math before you advance.
Example entry. Maria’s gross receipts of 42318.55 minus deductions of 0.00 yields taxable receipts of 42318.55.
Nuance. If you have UEZ-qualifying sales, the portal asks for them on a separate line at half the standard rate (3.3125%). UEZ sales are removed from this line and entered separately so the rate is applied correctly.
Common mistake and consequence. Filers manually overwrite the calculated taxable receipts figure to “fix” rounding. The portal flags any override, and the Division opens a desk audit to reconcile the change.
Misconception. Filers believe taxable receipts and tax due are the same number. They are not. Taxable receipts are the base; the tax due is 6.625% of that base.
Field 7: Sales Tax Due
Plain English. This is the New Jersey sales tax you owe on the month’s taxable receipts.
How to answer it. Multiply taxable receipts by 6.625% (0.06625). The portal calculates this automatically. For UEZ sales, the system applies 3.3125%.
Example entry. Lopez Boutique’s taxable receipts of $42,318.55 produce sales tax due of $2,803.60.
Nuance. The amount you collected at the register may differ slightly from the calculated 6.625% due to rounding on individual receipts. The Division of Taxation accepts the calculated amount as the floor; over-collections must still be remitted under N.J.S.A. 54:32B-12.
Common mistake and consequence. Filers remit only what the cash drawer collected, even when the calculated tax is higher. The shortfall becomes an underpayment, and a 5% late-payment penalty plus interest applies to the difference.
Misconception. Filers assume the state will refund any over-collected tax automatically. It will not. Over-collected tax must be either refunded to the customer or remitted to the state — keeping it is a violation under N.J.S.A. 54:32B-14.
Field 8: Use Tax Due
Plain English. Use tax is the 6.625% you owe on items you bought from out-of-state vendors that did not charge New Jersey sales tax, when you used those items in New Jersey.
How to answer it. Add the taxable purchase price of each out-of-state item, multiply by 6.625%, and enter the total.
Example entry. Marcus bought $850 of detailing chemicals from an out-of-state online supplier with no NJ tax charged. He enters 56.31 in the use tax field.
Nuance. Use tax applies even to a single online purchase. Many small businesses miss this entirely, then face a use tax assessment during a sales tax audit.
Common mistake and consequence. Filers leave the use tax field at zero out of habit. On audit, the Division pulls credit card statements and assesses unpaid use tax going back four years, plus penalty and interest.
Misconception. Filers believe use tax only applies to large equipment. It applies to any taxable item — office supplies, software, parts, inventory used in the business — purchased without NJ tax.
Field 9: Total Amount Due
Plain English. This is the total payment owed: sales tax due plus use tax due.
How to answer it. The portal sums Fields 7 and 8 automatically. Confirm the total before submitting.
Example entry. Maria’s total amount due is 2803.60. Marcus’s is 56.31 plus his sales tax of 1245.78, for a total of 1302.09.
Nuance. The portal does not allow partial payments on ST-51. If you cannot pay the full amount, the Division of Taxation directs you to the installment payment plan request after the return is filed.
Common mistake and consequence. Filers submit the return without authorizing the ACH debit, thinking they will mail a check later. The return posts as filed but unpaid, and the 5% late-payment penalty starts the next day.
Misconception. Filers believe filing the return alone protects them from penalties. Filing without paying triggers the late-payment penalty even when the return is on time.
Field 10: Payment Authorization
Plain English. This is where you authorize the state to pull the payment from your bank account or accept your credit card.
How to answer it. Choose ACH debit (free), e-check (free), or credit card (a 1.95% to 2.45% convenience fee applies through the third-party processor). Enter your routing and account numbers carefully.
Example entry. Aisha Patel selects ACH debit, enters routing number 021000021 and account number 9876543210, and schedules the debit for the filing date.
Nuance. ACH debits scheduled for a future date — up to the 20th — are allowed. The portal holds the return as “filed” but the cash does not leave the account until the scheduled date.
Common mistake and consequence. Filers transpose digits in the bank account number. The bank rejects the debit, the state assesses a $50 returned-payment fee, and the filing is treated as unpaid until cleared.
Misconception. Filers believe a credit card payment posts instantly with no consequence if the card is later disputed. A chargeback reverses the payment, and the Division reinstates the unpaid balance with full penalty and interest.
Field 11: Confirmation Number
Plain English. After you submit, the portal displays a confirmation number. Save it.
How to answer it. Print the confirmation page, screenshot it, or copy the number into your accounting software with the period ending date.
Example entry. Marcus saves confirmation number STX-20260220-118473 in his QuickBooks memo field for January 2026.
Nuance. The confirmation is the only proof of timely filing the Division accepts in a dispute. The portal does not email it automatically — you must capture it on the screen.
Common mistake and consequence. Filers close the browser before saving the confirmation number. If the Division later claims the return was not filed, the filer has no defense and pays the late-filing penalty.
Misconception. Filers think the bank’s ACH withdrawal record proves filing. It only proves payment. The confirmation number is the proof of the return filing.
Three Filled-Out Examples Using Real Scenarios
The three filers below run different businesses but all file ST-51 for January 2026, due February 20, 2026.
Scenario 1: Maria Lopez — Lopez Boutique LLC, a small retailer
| Form Section | What Maria Enters |
|---|---|
| NJ Taxpayer ID | 123456789000 |
| PIN | 4827 |
| Period Ending Date | 01/31/2026 |
| Gross Receipts | 42318.55 |
| Deductions | 0.00 |
| Taxable Receipts | 42318.55 |
| Sales Tax Due (6.625%) | 2803.60 |
| Use Tax Due | 0.00 |
| Total Amount Due | 2803.60 |
| Payment Method | ACH debit, scheduled 02/20/2026 |
| Confirmation Number Saved | STX-20260218-094221 |
Scenario 2: Marcus Bell — Bell’s Auto Detailing, a service business with use tax
| Form Section | What Marcus Enters |
|---|---|
| NJ Taxpayer ID | 987654321000 |
| PIN | 3162 |
| Period Ending Date | 01/31/2026 |
| Gross Receipts | 19815.00 |
| Deductions (ST-4 fleet sales) | 1200.00 |
| Taxable Receipts | 18615.00 |
| Sales Tax Due (6.625%) | 1233.24 |
| Use Tax Due (out-of-state chemicals $850) | 56.31 |
| Total Amount Due | 1289.55 |
| Payment Method | E-check |
| Confirmation Number Saved | STX-20260219-110934 |
Scenario 3: Aisha Patel — Patel Hardware, a UEZ-certified shop in Newark
| Form Section | What Aisha Enters |
|---|---|
| NJ Taxpayer ID | 456789123000 |
| PIN | 7715 |
| Period Ending Date | 01/31/2026 |
| Gross Receipts | 28450.00 |
| UEZ Qualifying Sales (taxed at 3.3125%) | 22000.00 |
| Standard-Rate Taxable Sales | 6450.00 |
| Sales Tax Due (UEZ portion) | 728.75 |
| Sales Tax Due (standard portion at 6.625%) | 427.31 |
| Use Tax Due | 0.00 |
| Total Amount Due | 1156.06 |
| Payment Method | ACH debit |
Janet Romero, who runs a remote-seller online shop based in Pennsylvania but ships into New Jersey under economic nexus, and Carlos Rivera, who operates a Jersey City restaurant, would follow the same field order with their own numbers. All five filers use identical screens.
How to File the Completed Form
There are two approved ways to file ST-51, and both are electronic. New Jersey law forbids paper ST-51 submissions, and any paper return is returned to the sender unprocessed under the rules at N.J.A.C. 18:2-2.
Online portal. Go to the Sales and Use Tax Online Filing page, log in with your 12-digit Taxpayer ID and PIN, and follow the prompts. There is no filing fee. ACH debit and e-check are free; credit card payments through the NICUSA payment processor carry a 1.95% to 2.45% convenience fee. Returns submitted before 11:59 p.m. Eastern on the 20th are timely. The confirmation number appears on the final screen — save it before closing.
Telephone filing. Call 1-877-829-2866, enter your Taxpayer ID and PIN at the prompts, and follow the voice menu. The system supports ACH debit only. There is no fee. The system reads back a confirmation number at the end of the call — write it down because no paper receipt is mailed.
Processing time. The return posts to your tax account within 24 to 48 hours. ACH debits clear in two to three business days. Credit card payments post the same day. Once the payment clears, the Division of Taxation account view updates the period status to “Filed and Paid.”
Proof of filing. Keep three pieces of evidence: the confirmation number, the bank statement showing the debit, and a printed PDF of the filing screen. The Division of Taxation requires three years of retention under N.J.A.C. 18:24-10.4, but most CPAs recommend four years to match the audit lookback window.
What Happens After You File
Within minutes of submission, the portal locks the period as “Filed.” The filing posts to your tax account, and the period appears in the Premier Business Services account view with the date, amount, and confirmation number.
The ACH debit clears in two to three business days. If the debit fails because of insufficient funds or a wrong account number, the Division mails a returned-payment notice with a $50 fee, and the filing reverts to unpaid status. You then have 10 days to remit by certified funds before the late-payment penalty applies.
At the end of the quarter, the ST-51 prepayments roll into the Form ST-50 reconciliation. The portal automatically pulls the two ST-51 prepayments into the ST-50 worksheet, and the filer enters month-three sales to compute the final balance. If ST-51 was overpaid, the credit applies against ST-50; if underpaid, the balance is due with ST-50.
The Division of Taxation runs an automated cross-match between ST-51 reported gross receipts and the seller’s federal Form 1099-K and federal income tax return. A material mismatch triggers a desk audit letter, usually 9 to 18 months after filing. Keeping organized monthly worksheets is the easiest defense.
Mistakes to Avoid When Filling Out the Form
- Choosing the wrong period ending date. Selecting February 28 instead of January 31 misposts the payment, and the January period stays unpaid with penalties accruing.
- Filing ST-51 for March, June, September, or December. These months are reported on ST-50 only. The portal blocks the filing, but filers waste hours trying.
- Skipping ST-51 when tax collected exceeds $500. The Division charges a 5% late-filing penalty and 5% late-payment penalty when the missing month surfaces on ST-50.
- Including sales tax inside gross receipts. Inflates the base and creates a reconciliation gap that a desk audit will flag.
- Deducting exempt sales without a signed exemption certificate. The deduction is disallowed on audit, and full tax plus penalty is assessed.
- Leaving use tax at zero. Almost every business buys taxable items from out-of-state vendors. Zero use tax invites a use tax audit.
- Transposing bank account digits. The $50 returned-payment fee plus the late-payment penalty applies until the corrected payment clears.
- Closing the browser before saving the confirmation number. Without the confirmation number, the filer has no proof of timely filing.
- Using the FEIN alone instead of the 12-digit Taxpayer ID. The portal locks the account after three failed logins, costing valuable time near the deadline.
- Filing on the 20th at 11:55 p.m. Browser slowness, expired sessions, and last-minute portal traffic crashes cause real losses; aim for the 18th at the latest.
- Forgetting UEZ rate splits. A UEZ-certified business that runs all sales through the standard 6.625% line over-collects and over-remits, and customers may sue for refunds.
- Misreading the $500 threshold as quarterly. The threshold is monthly. Filers who think it is quarterly skip months they were required to file.
Do’s and Don’ts
Do’s
- Reconcile your POS report to your bank deposits before opening the portal, because mismatches cause restated returns.
- Save the confirmation number in three places (email, accounting software, paper file), since it is the only proof of timely filing.
- Schedule the ACH debit for the actual due date so you keep cash in your account longer without missing the deadline.
- File even when the month’s tax is exactly $500, because the Division of Taxation reads the threshold as “more than $500” and treating it conservatively avoids close-call disputes.
- Keep exemption certificates organized by customer and date, since auditors ask for them in chronological order.
- Update your bank routing number in the portal whenever you change banks, because old debits silently fail.
Don’ts
- Don’t paper-file ST-51, since the Division returns paper submissions unprocessed and you fall behind the deadline.
- Don’t combine two months of tax into one ST-51 filing, because each month is a separate return with its own period ending date.
- Don’t deduct bad-debt write-offs on ST-51, since bad debt is reported only on the quarterly ST-50 under N.J.S.A. 54:32B-12.1.
- Don’t ignore the use tax field, because the Division pulls credit card and bank records during audits and back-bills four years of unpaid use tax.
- Don’t share your PIN with employees who turn over often, since former employees can file fraudulent returns under your account.
- Don’t rely on the prior month’s gross receipts as a “good enough” estimate, because estimated returns are automatically flagged for review.
Pros and Cons of Filing on Your Own vs. With Help
Pros of filing ST-51 yourself
- The form is short, with fewer than fifteen fields, so a small business owner can finish in ten minutes once the data is ready.
- There is no filing fee, and ACH debit is free, so the only cost is your time.
- You build direct knowledge of your sales tax position, which helps you spot errors earlier in the month.
- You control the timing of the debit, which protects cash flow during slow weeks.
- The portal saves prior returns, so each filing gets faster as your records accumulate.
Cons of filing ST-51 yourself
- A single misclassified deduction can cost more in penalty and interest than a year of CPA fees.
- The 20-minute portal timeout punishes filers who multitask, and lost sessions force a restart.
- Use tax is easy to miss without a trained eye, and the four-year audit lookback compounds the risk.
- UEZ rate splits and remote-seller nexus questions are technical, and filers without tax training often get them wrong.
- The Division of Taxation does not accept “I made a mistake” as a penalty defense, so DIY errors carry full statutory consequences under N.J.S.A. 54:49-4.
Paper vs. Online Filing
| Filing Method | New Jersey ST-51 Status |
|---|---|
| Paper Form Mailed | Not accepted; returns unprocessed under N.J.A.C. 18:2-2 |
| Online Portal | Required for all filers, free ACH/e-check, fee for credit card |
| Phone (1-877-829-2866) | Allowed, ACH debit only, no fee |
| In Person at Trenton Office | Not accepted for ST-51 |
| Fax | Not accepted |
ST-51 vs. ST-50 at a Glance
| Feature | ST-51 (Monthly) vs. ST-50 (Quarterly) |
|---|---|
| Frequency | ST-51 monthly for months 1 and 2 of a quarter; ST-50 quarterly |
| Trigger | ST-51 only when monthly tax exceeds $500; ST-50 always |
| Reconciliation | ST-51 is a prepayment; ST-50 is the final return |
| Bad Debt Deduction | Not allowed on ST-51; allowed on ST-50 |
| Due Date | ST-51 due 20th of next month; ST-50 due 20th of month after quarter end |
FAQs
Do I file ST-51 if I collected exactly $500 in sales tax for the month?
No. The threshold is more than $500, so $500.00 flat does not require ST-51. Report that month’s tax on the next ST-50.
Can I file a paper ST-51 if my internet is down?
No. New Jersey requires electronic filing. Use the phone system at 1-877-829-2866 or file from another internet connection before the 20th.
What do I enter in the period ending date if I am paying January tax in February?
Yes, enter 01/31/2026, the last day of the month the tax was collected. The filing date is separate from the period date.
Do I report use tax on ST-51 or only on ST-50?
Yes, use tax goes on ST-51 in the use tax field whenever you have qualifying out-of-state purchases for that month. ST-50 reconciles the quarter total.
Is the sales tax rate still 6.625% in 2026?
Yes, the New Jersey statewide rate remains 6.625%, with UEZ-certified retail sales at 3.3125%, per the Division of Taxation rate notice.
Do I deduct customer refunds in the deductions box on ST-51?
No. Reduce gross receipts by refunds issued the same month, but do not list refunds on the deductions line, which is reserved for exempt sales.
What if I forget to file ST-51 but pay the full amount on ST-50?
No, that does not avoid the penalty. The 5% late-filing penalty for the missed month still applies even when ST-50 captures the tax.
Can I amend an ST-51 after I submit it?
Yes, corrections happen on the next ST-50 reconciliation, since ST-51 is a prepayment. There is no separate amended ST-51 form.
Do remote sellers under economic nexus file ST-51?
Yes, if monthly NJ tax collected exceeds $500. Crossing the $100,000 or 200-transaction threshold creates the same monthly filing duty as in-state sellers.
What if I write my FEIN instead of my 12-digit Taxpayer ID in the login?
No, the FEIN alone fails. Add your three-digit location suffix to make 12 digits, or the portal will reject the login.
Do I include Amazon or Etsy sales in gross receipts on ST-51?
No, if those marketplaces collect and remit NJ tax for you under marketplace facilitator rules. Include only sales where you collected the tax directly.
Can my bookkeeper file ST-51 for me without a power of attorney?
Yes, if you give them your Taxpayer ID and PIN. For audit defense and refund claims, file a Form M-5008-R power of attorney to formalize representation.
Related reading
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