How to Fill Out Texas Form AP-178 (w/Examples) + FAQs

Texas Form AP-178, the Texas Application for Payee Identification Number, is the form an individual, sole proprietor, partnership, corporation, or other entity files with a Texas state agency to receive a Texas Identification Number (TIN) so the state can issue payments through the Comptroller’s Texas Identification Number System. Without a valid TIN on file, no state agency can legally cut a check, run a direct deposit, or issue a 1099 to the payee, which is why the Texas Comptroller of Public Accounts treats AP-178 as the gatekeeper to every vendor and contractor payment in Texas.

The Texas Comptroller processes more than 17 million payments per year through TINS, and a missing or mismatched AP-178 is the single most common reason a payment gets held in suspense status. This guide walks through the current revision (Rev. 4-23) of Form AP-178 line by line so you can clear that gate the first time.

📝 How to complete every box on AP-178 without triggering an IRS name/TIN mismatch
💰 Which Ownership Code to pick so backup withholding does not eat 24% of your payment
📬 Where to send the form, who actually keys it into TINS, and how long approval takes
🧾 Three full filled-out walkthroughs for an independent contractor, an LLC vendor, and a nonresident alien
⚠️ The 10 most common AP-178 mistakes and the exact consequence each one creates

What the Form Is and Who Must File It

Form AP-178 is the Texas Application for Payee Identification Number, a one-page application maintained by the Texas Comptroller of Public Accounts under the authority of Texas Government Code Chapter 403, which makes the Comptroller the state’s chief accountant and disbursing officer. The form’s job is to feed the Comptroller’s Texas Identification Number System (TINS) the legal name, taxpayer identification number, ownership type, and mailing address of any person or entity that will receive a payment from a Texas state agency.

Anyone who expects payment from a state agency must file it. That includes sole proprietors selling office supplies to a state university, attorneys taking court appointments paid through a district court, grant recipients at nonprofits, foster parents reimbursed by the Texas Department of Family and Protective Services, medical providers billing Medicaid through HHSC, employees of state agencies who need travel reimbursement, jurors, expert witnesses, and any out-of-state vendor selling to Texas. The form is also filed when an existing payee needs to update ownership information, change a legal name, or correct an address already in TINS.

Federal law sits behind the form too. The IRS requires the state to issue Form 1099-MISC or 1099-NEC to most non-employee payees, and an incorrect Taxpayer Identification Number on AP-178 will trigger a B-Notice and 24% backup withholding under IRC §3406. That is the real teeth behind the form: get the name and TIN combination wrong, and the state must legally hold back nearly a quarter of every payment until the mismatch is cured.

Before You Start: Documents and Information You Need

Filling out AP-178 is fast when the paperwork is already on your desk and miserable when it is not. The Comptroller will not accept a form that is missing the TIN, the signature, or the ownership code, so gather everything below before you open the PDF. The official fillable version of Form AP-178 lives on the Comptroller’s website, and the companion direct deposit authorization Form 74-176 is almost always submitted at the same time.

Social Security Number or Employer Identification Number. The state cross-checks this against IRS records using the TIN Matching program, so a typo here means automatic rejection.
Legal name exactly as filed with the IRS. For individuals, it must match the SSA card; for entities, it must match the SS-4 confirmation letter, since any deviation will cause a name/TIN mismatch.
Current IRS Form W-9. Most state agencies require it as an attachment so the federal taxpayer name flows cleanly into the 1099 system.
DBA or assumed name certificate. If you do business under a name that is different from your legal name, the Texas Secretary of State assumed name filing supports the entry in Box 4.
Ownership documentation. Articles of incorporation, an LLC certificate of formation, or a partnership agreement establishes which Ownership Code box applies.
Mailing address and physical address. The state mails warrants (paper checks) to the address on AP-178, and a P.O. Box without a street address can delay delivery.
Phone number and email. The agency’s payable team uses these to clear holds, and a missing contact can stall a payment for weeks.
Direct deposit information. A voided check or bank letter is needed for the companion Form 74-176 if the payee wants electronic payment instead of a paper warrant.
State agency contact. The name of the agency requesting the form, a contact person there, and the agency’s three-digit number help the form reach the right desk.
Authorized signer. For entities, the signer must have authority to bind the business, which usually means an officer, partner, or member.

Where to Get the Form and How to Access It

The single authoritative source for AP-178 is the Texas Comptroller forms library, where the current Rev. 4-23 PDF is posted as a fillable document. Downloading the form from any other website risks pulling an outdated version, and TINS staff will reject any AP-178 that uses an obsolete revision because field labels and ownership codes change between revisions.

The fillable PDF can be completed inside Adobe Acrobat Reader, printed, signed, and either scanned or mailed to the requesting state agency. The Comptroller does not accept AP-178 directly from payees; the requesting agency keys the form into TINS through the Uniform Statewide Accounting System (USAS) on the payee’s behalf. That means the workflow is payee → state agency → Comptroller, not payee → Comptroller.

Some larger agencies post their own AP-178 intake portals. The University of Texas System, the Texas A&M University System, and HHSC vendor enrollment all have secure upload pages that route the signed PDF to the agency’s accounts payable team. Smaller agencies still take fax or mail. Always confirm the channel with the agency contact before sending, because emailing an unencrypted PDF that contains an SSN is a security violation under Texas Business and Commerce Code §521.052.

Step-by-Step: How to Fill Out Form AP-178 Line by Line

The following walkthrough follows the current Rev. 4-23 of Form AP-178 field by field. Use the exact box numbers and labels printed on the form, since the agency’s data entry team enters the form into TINS using those same labels under guidance from the TINS Guide Section 1.

Box 1 — Texas Identification Number (TIN)

This box asks for the 11-digit Texas Identification Number the Comptroller has already assigned to you, if any. New payees leave it blank because TINS will generate the number once the form is processed. Existing payees who are updating information must enter the number exactly as it appears on prior payment vouchers.

To answer it, write the 11 digits with no dashes, no spaces, and no leading words. Maria Lopez, who has never been paid by Texas before, leaves Box 1 empty. If she had a prior TIN of 17412345678, she would write that number in the box.

The most common nuance is a payee who has been paid before but does not know the TIN; the requesting agency can look it up in TINS using the SSN or EIN, so do not guess. The common mistake is entering a federal EIN here instead of the state TIN, which causes the form to reject because TINS expects 11 digits, not 9. A misconception is that the TIN is the same as the EIN; it is not — the state TIN is built from the federal TIN plus a check digit and a sequence digit assigned by TINS.

Box 2 — Type of Identification Number

This box asks which kind of federal taxpayer identifier you are providing: a Social Security Number, an Employer Identification Number, or an Individual Taxpayer Identification Number. Check exactly one box.

To answer, mark SSN for individuals and most sole proprietors, EIN for entities and sole proprietors who have applied for one, or ITIN for nonresident aliens who lack SSN eligibility. Maria Lopez, a sole proprietor consultant, checks SSN because she has never applied for an EIN.

The nuance is that a sole proprietor with employees must have an EIN under IRS rules, so that filer checks EIN even though the business is unincorporated. The common mistake is checking SSN and then writing an EIN in Box 3, which causes an immediate name/TIN mismatch in the IRS TIN Matching system. The misconception is that an ITIN works for any nonresident; in reality, foreign entities use a Foreign Tax Identification Number, not an ITIN.

Box 3 — The Identification Number Itself

This box wants the nine-digit number that matches the type checked in Box 2. Write it with the standard formatting the IRS uses: SSNs as XXX-XX-XXXX, EINs as XX-XXXXXXX, and ITINs as 9XX-XX-XXXX starting with a 9.

To answer, copy the number directly from the source document — the Social Security card, the IRS SS-4 confirmation letter (CP-575), or the ITIN assignment notice (CP-565). Carlos Ramirez writes 75-1234567 because that is the EIN on the CP-575 he received from the IRS for Ramirez Consulting LLC.

The nuance is that a single-member LLC owned by an individual is a disregarded entity for federal tax purposes, so the IRS expects the owner’s SSN here, not the LLC’s EIN, even though the LLC has one. The common mistake is writing the LLC’s EIN when the LLC is disregarded, which guarantees a B-Notice and 24% backup withholding. The misconception is that the EIN belongs on the form because that is the number on the LLC’s bank account; tax law does not care about the bank, only about the IRS classification.

Box 4 — Name (Last, First, Middle for Individuals; Legal Entity Name for Businesses)

This box captures the legal name the IRS associates with the TIN in Box 3. For individuals, enter last name, then first name, then middle initial. For entities, enter the full legal name from the formation document.

To answer, individuals copy the name as printed on the Social Security card, including suffixes like Jr. or III. Entities copy the name from the certificate of formation. Janet Williams enters Williams, Janet K. because that is exactly how her Social Security card reads.

The nuance is married filers who have not updated the SSA after a name change; they must enter the maiden name here even if they prefer the married name socially, because the IRS still has the maiden name on file. The common mistake is using a DBA or trade name in this box, which produces a name/TIN mismatch because the DBA is not registered with the IRS. The misconception is that the state will figure out the right name from context; TINS does not — it sends an exact-match query to the IRS, and any deviation fails.

Box 5 — Mailing Address

This box wants the address where the state should mail correspondence and paper warrants. Enter street, city, state, and ZIP+4 if known.

To answer, write the address one line at a time exactly as the USPS ZIP Code lookup would format it, since the Comptroller cleans addresses against USPS standards. Maria Lopez writes 1428 Brazos St., Austin, TX 78701-2245.

The nuance is that a P.O. Box is acceptable for the mailing address but cannot be the only address on file if the payee will receive a 1099 with a physical address requirement. The common mistake is putting a suite number on a separate line that the agency drops during data entry, which sends the warrant to the wrong floor. The misconception is that a typo can be fixed by the bank; banks return mismatched warrants to the state, and recovering one takes weeks.

Box 6 — Ownership Code

This box is the one filers get wrong most often. The Ownership Code tells TINS what kind of legal entity the payee is, and it controls how the state issues a 1099 at year end. The codes are listed on the back of Form AP-178 and in the TINS Ownership Codes table.

To answer, pick exactly one code: I for individual recipient, S for sole owner, P for partnership, C for Texas corporation, F for financial institution, G for governmental entity, L for professional association, O for out-of-state corporation, U for state agency, N for nonprofit, or X for foreign. Carlos Ramirez, whose Ramirez Consulting LLC is taxed as an S-corporation, checks C because TINS treats S-corp LLCs as corporations for 1099 purposes.

The nuance is that LLCs are not their own ownership code; the filer must pick the federal tax classification of the LLC (disregarded → I or S, partnership → P, corporation → C). The common mistake is picking S (sole owner) for any LLC, which misclassifies multi-member or corporate LLCs and produces an incorrect 1099. The misconception is that the code only matters for tax forms; in fact, the code also controls whether the payee is exempt from 1099 reporting at all.

Box 7 — Phone Number and Email

This box collects the contact information the state uses to clear payment holds. Enter the area code, number, extension if any, and a monitored email address.

To answer, use a number and inbox a human actually checks daily, because TINS holds get cleared by phone. Janet Williams writes 512-555-0142 and janet.williams.cpa@gmail.com.

The nuance is that an entity should list the accounts receivable contact, not the owner’s cell, since AR will be the one fielding hold notices. The common mistake is leaving email blank, which forces the agency to mail a hold letter and adds two weeks to resolution. The misconception is that the phone number is private; it becomes part of the state’s vendor record, which is subject to the Texas Public Information Act.

Box 8 — Security Question and Answer

Newer revisions of AP-178 include a security question used by the agency to verify the payee on later phone calls. Pick a question and write the exact answer.

To answer, choose something memorable but not guessable from public records. Maria Lopez picks the mother’s maiden name question and writes Salazar.

The nuance is that any agent at the requesting agency can later ask the question to authorize a change, so do not pick an answer printed on social media. The common mistake is writing an answer in a different format than the filer remembers, like Mom instead of the full last name, which causes a verification failure. The misconception is that this question is optional; some agencies treat it as required even when the form does not.

Box 9 — Signature, Title, and Date

This is the legal certification that the information is accurate under penalty of perjury. The form must be signed in ink (or with a compliant e-signature) by an authorized person.

To answer, sign on the line, print the title (Owner, Member, President, CFO, etc.), and write the date in MM/DD/YYYY format. Carlos Ramirez signs his name, prints Managing Member, and dates the form 05/14/2026.

The nuance is that a tax preparer cannot sign for the payee unless a power of attorney is on file. The common mistake is signing but forgetting to date, which is grounds for rejection by TINS data entry staff. The misconception is that a typed name in Acrobat is always acceptable; some agencies still require a wet signature, so confirm with the requesting agency before submitting.

Box 10 — State Agency Use Only

This block is reserved for the state agency’s accounts payable team. The payee leaves it blank.

To answer, do nothing here. Maria Lopez writes nothing in Box 10 and lets the University of Texas accounts payable clerk fill it in.

The nuance is that filling it in anyway is not a rejection trigger, but it confuses the agency clerk who must overwrite the data. The common mistake is treating Box 10 as the agency contact field and putting the payee’s own information there. The misconception is that this section is optional for the agency too; it is not, since the agency must record the assignment date and the keying employee for audit under TINS internal controls.

Three Filled-Out Examples Using Real Scenarios

The walkthroughs below show three of the most common AP-178 fact patterns. Each scenario follows one named filer through the form using the exact field names from Rev. 4-23.

Scenario 1 — Maria Lopez, Independent Consultant Hired by UT Austin

Maria is a sole proprietor with no employees, hired by UT Austin to deliver a curriculum review for $8,500. She files AP-178 because the university’s accounts payable team will not cut the check without a TIN.

Form Section	What Maria Enters
Box 1 — Texas Identification Number	(blank — no prior TIN)
Box 2 — Type of ID Number	SSN
Box 3 — Identification Number	468-22-1190
Box 4 — Name	Lopez, Maria E.
Box 5 — Mailing Address	1428 Brazos St., Austin, TX 78701-2245
Box 6 — Ownership Code	I — Individual Recipient
Box 7 — Phone / Email	512-555-0142 / maria.lopez.consulting@gmail.com
Box 8 — Security Q/A	Mother’s maiden name / Salazar
Box 9 — Signature/Title/Date	Maria E. Lopez / Owner / 05/14/2026

Scenario 2 — Ramirez Consulting LLC, S-Corp Vendor Selling Software to HHSC

Carlos Ramirez owns Ramirez Consulting LLC, which has elected S-corporation tax treatment under IRS Form 2553. The LLC is selling a software license to HHSC for $42,000 over a year.

Form Section	What Carlos Enters
Box 1 — Texas Identification Number	(blank — new vendor)
Box 2 — Type of ID Number	EIN
Box 3 — Identification Number	75-1234567
Box 4 — Name	Ramirez Consulting LLC
Box 5 — Mailing Address	3300 Bee Caves Rd., Suite 650, Austin, TX 78746-5380
Box 6 — Ownership Code	C — Corporation
Box 7 — Phone / Email	512-555-0388 / ar@ramirezconsulting.com
Box 8 — Security Q/A	First school attended / Roosevelt Elementary
Box 9 — Signature/Title/Date	Carlos A. Ramirez / Managing Member / 05/14/2026

Scenario 3 — Dr. Anya Petrov, Nonresident Alien Expert Witness in a Texas District Court

Dr. Petrov, a Canadian neurologist, has been retained as an expert witness in a Travis County medical malpractice case. The court will pay her a $3,200 fee from the Office of Court Administration.

Form Section	What Anya Enters
Box 1 — Texas Identification Number	(blank — first Texas payment)
Box 2 — Type of ID Number	ITIN
Box 3 — Identification Number	912-77-4421
Box 4 — Name	Petrov, Anya
Box 5 — Mailing Address	55 Bloor St. W., Toronto, ON M4W 1A5, Canada
Box 6 — Ownership Code	X — Foreign
Box 7 — Phone / Email	416-555-0921 / dr.petrov@neuroclinic.ca
Box 8 — Security Q/A	City of birth / Saint Petersburg
Box 9 — Signature/Title/Date	Anya Petrov / Self / 05/14/2026

How to File the Completed Form

AP-178 is filed to the requesting state agency, not to the Comptroller. The agency’s accounts payable team keys the data into TINS through USAS, and only then does the Comptroller assign the 11-digit TIN. The choice of channel depends on what the agency accepts.

Mail. Fold the signed form into a #10 envelope and address it to the agency’s accounts payable office. The exact address is on the agency’s vendor onboarding page, such as the UT System Payment Services or the Texas A&M System Business Office. There is no filing fee. Processing takes 7 to 14 business days. Keep the USPS Certified Mail receipt as proof of filing.
Secure upload portal. Most large agencies, including HHSC’s Provider Claims Services and TxDOT Vendor Services, have an encrypted upload page. There is no fee. Processing usually takes 3 to 7 business days. Save the confirmation email as proof.
In person. Walk the form to the agency’s accounts payable counter at its Austin headquarters or regional office. There is no fee. Processing can be same-day if the clerk keys it on the spot. Ask for a date-stamped copy as proof.
Fax. Some smaller agencies still accept fax to a dedicated payable line published on their vendor page. There is no fee. Processing takes 5 to 10 business days. Keep the fax confirmation page as proof.
Email — only when explicitly authorized and encrypted. A few agencies accept a password-protected PDF emailed to a dedicated AP inbox. Never email an unprotected PDF that contains a Social Security Number, since that violates Texas Business and Commerce Code §521.052.

Direct deposit is set up separately by submitting the Direct Deposit Authorization Form 74-176 to the same agency. Payment by ACH usually arrives in two business days, while a paper warrant can take 7 to 10 days in the mail.

What Happens After You File

Once the agency keys AP-178 into TINS, the Comptroller’s system runs an IRS TIN Matching check overnight. A clean match produces an active TIN and the payee’s record moves to active status, which clears the way for any payment voucher the agency cuts. A failed match generates a TINS suspense entry and the payment is held until the agency or payee corrects the underlying field.

The payee receives no automatic confirmation letter from the Comptroller. The requesting agency notifies the payee that the TIN is active, usually by email from the AP team. Payees can verify their own status by asking any state agency to look them up in TINS by SSN or EIN, since TINS is shared across all 200+ Texas state agencies.

If a payment is held, the agency mails a TINS hold letter describing the field that failed. The payee fixes the field by submitting a corrected AP-178 marked as an update. Most holds clear within 5 business days of the corrected form. A B-Notice from the IRS, by contrast, takes 30 to 60 days to clear and will trigger 24% backup withholding on every payment until resolved, under IRC §3406.

Mistakes to Avoid When Filling Out the Form

Writing an EIN when Box 2 is checked SSN. TINS rejects the form on data entry, delaying payment by at least one cycle.
Using a DBA in Box 4 instead of the legal name. The IRS TIN Matching call fails and triggers backup withholding.
Picking Ownership Code S for a multi-member LLC. The 1099 issues to the wrong classification and the filer must amend.
Leaving Box 9 unsigned or undated. The agency rejects the form on intake and the payee has to start over.
Entering a P.O. Box with no street address when a 1099-NEC will be issued. The IRS bounces the 1099 and the payee gets a notice.
Submitting an obsolete revision of the form. TINS staff reject anything older than the current Rev. 4-23 because field positions changed.
Emailing an unencrypted PDF with an SSN. This violates Texas Business and Commerce Code §521.052 and can lead to identity-theft notices.
Forgetting to attach the W-9 when the agency requires it. The agency holds the form until the W-9 arrives, adding 5 business days.
Mismatching the name on AP-178 and the name on Form 74-176. Direct deposit setup fails and the bank rejects the ACH.
Listing the owner’s personal cell with no email. Hold letters can take two weeks to reach the payee, stretching resolution time.

Do’s and Don’ts

Do match the name in Box 4 letter-for-letter to the SSA card or IRS CP-575, because IRS TIN Matching is exact-match only.
Do use the current Rev. 4-23 PDF from the Comptroller forms page, since older revisions are rejected on sight.
Do confirm the right Ownership Code by reading the TINS Ownership Codes table before checking a box.
Do submit AP-178 and Form 74-176 together so direct deposit and TIN setup are processed in parallel.
Do keep a signed copy and proof of delivery for at least four years, which matches the IRS recordkeeping window.
Do call the requesting agency’s AP line if the form has not cleared after 14 business days, since silent holds happen.
Don’t sign the form in pencil or use white-out, because TINS staff treat it as altered and reject it.
Don’t email an unencrypted SSN, since it violates Texas Business and Commerce Code §521.052.
Don’t assume the LLC’s EIN is the right number when the LLC is a disregarded entity for federal tax.
Don’t put a DBA, trade name, or marketing name in Box 4, since only the IRS legal name belongs there.
Don’t leave Box 8 blank if the agency’s vendor packet says it is required, even when the PDF marks it optional.
Don’t submit AP-178 directly to the Comptroller; the form must go through the requesting agency.

Pros and Cons of Filing on Your Own vs. With Help

Filing AP-178 is short, but the consequences of an error are big enough that some payees hire a CPA or use the requesting agency’s vendor onboarding service. The right choice depends on the filer’s comfort with IRS classification rules.

Pro of filing on your own: Zero cost beyond the time to read the form.
Pro of filing on your own: Faster turnaround, since you can submit the same day.
Pro of filing on your own: Direct control over what shows up in the state’s vendor record.
Pro of filing on your own: Most fields are simple identity information that any adult can complete.
Pro of filing on your own: The agency’s AP team will often coach you through Box 6 if you call.
Con of filing on your own: Picking the wrong Ownership Code can trigger IRS backup withholding under IRC §3406.
Con of filing on your own: A name mismatch on Box 4 produces a B-Notice that takes months to clear.
Con of filing on your own: Out-of-state and foreign entities face tax-treaty rules that are easy to miss.
Con of filing on your own: Disregarded-entity LLC owners often pick the wrong number for Box 3.
Con of filing on your own: Errors on AP-178 propagate into every 1099 the state issues, multiplying the cleanup work.

Filing by Mail vs. Online: Which Channel Wins

Filing Channel	Best Fit
Mail to agency AP office	Vendors without a portal login or who need a paper trail by Certified Mail
Secure agency upload portal	Most modern vendors, fastest processing, best audit trail
In-person hand delivery	Local Austin vendors who need same-day TIN activation
Fax to dedicated AP line	Smaller agencies or rural vendors without scanner access
Encrypted email (when authorized)	One-off payees with no portal access and authorized AP contact

FAQs

Do I file Form AP-178 with the Comptroller or with the agency paying me?

No. AP-178 is submitted to the requesting state agency, which then keys it into TINS through USAS, so the Comptroller never receives the paper form directly from a payee.

Is there a filing fee for AP-178?

No. The Comptroller charges nothing to set up a payee record, and no Texas state agency is allowed to charge a payee a fee to be added to TINS.

Do I need a W-9 if I already filed AP-178?

Yes. Most state agencies require a current IRS Form W-9 alongside AP-178 because federal 1099 reporting is governed by IRS rules, not by Texas TINS rules.

Should I check SSN or EIN in Box 2 if I am a single-member LLC?

Yes. If the LLC is a disregarded entity, check SSN and use the owner’s SSN; the IRS treats the LLC as the owner for tax purposes regardless of the LLC’s EIN.

Do I write my legal name or my DBA in Box 4?

No. Never use a DBA in Box 4; the box requires the legal name on file with the IRS, and a DBA will fail TIN Matching every time.

Can I leave Box 1 blank if I have never been paid by Texas before?

Yes. New payees leave the Texas Identification Number box blank because TINS generates the 11-digit number after the agency keys the form.

Is Ownership Code S the right pick for any small business?

No. Code S means sole owner and only fits unincorporated sole proprietors; LLCs, partnerships, and corporations have their own codes that control 1099 treatment.

Will an unsigned form still be processed if the rest is correct?

No. TINS data entry staff reject any AP-178 that lacks an ink or compliant electronic signature, because the signature is the perjury certification.

Can I use Adobe Acrobat to sign Box 9 electronically?

Yes. Most agencies accept a compliant Acrobat e-signature, but always confirm with the requesting agency, since some still require a wet signature on the warrant file.

Does AP-178 expire and need to be refiled?

No. Once a TIN is active in TINS, it stays active indefinitely, but a payee must refile AP-178 to update name, ownership, or address changes.

Should foreign vendors pick Ownership Code O or X in Box 6?

No. Code O is for out-of-state U.S. corporations; foreign entities and foreign individuals use Code X, which triggers the correct nonresident tax handling.

Do I have to attach a voided check to AP-178?

No. A voided check is attached to the separate Direct Deposit Authorization Form 74-176, not to AP-178 itself.

Can the IRS see what I put on AP-178?

Yes. The Comptroller runs the name and TIN through IRS TIN Matching, so the IRS effectively validates the same combination it already has on file.

Is the security answer in Box 8 case-sensitive when the agency calls to verify?

No. Most agencies treat the answer as case-insensitive, but the spelling must match, so write the answer the way you will remember saying it on the phone.

Related reading