The Illinois Environmental Protection Agency (IEPA) Air Pollution Permit Application is the document a person, business, or facility files with the IEPA Bureau of Air to get legal permission to build, modify, or operate equipment that releases pollutants into the air. You must file it before you build, change, or run any emission source in Illinois, or you risk daily civil penalties under the Illinois Environmental Protection Act.
Illinois reviews thousands of air permit applications each year, and the IEPA reports that incomplete submittals are the single biggest cause of delay, with completeness rejections affecting roughly one in three first-time filers. This guide walks you through the APC-200 series application forms line by line, shows three real examples, and explains how to avoid the mistakes that trigger 90-day delays.
- 📋 What each IEPA air permit type covers and which one fits your facility
- 🧮 How to calculate criteria pollutant and Hazardous Air Pollutant (HAP) emissions correctly
- 🏭 Step-by-step instructions for every box on the Construction/Operating Permit form
- 💵 Current fees, deadlines, and the 90-day completeness clock under 35 Ill. Adm. Code Part 201
- ⚠️ The 10 most common mistakes that get applications kicked back
What the Form Is and Who Must File It
The IEPA Air Pollution Permit Application is the formal request a source makes to operate or construct equipment that emits regulated air pollutants in Illinois. The form is governed by the Illinois Environmental Protection Act, 415 ILCS 5/9 and 5/39, and by 35 Ill. Adm. Code Part 201, which sets the substantive permit rules. The IEPA Bureau of Air in Springfield processes the form.
You must file if you own or operate any equipment that emits a regulated pollutant — including criteria pollutants like PM, PM10, PM2.5, NOx, SO2, CO, VOC, and lead, plus the 187 federal Hazardous Air Pollutants. The trigger is broad. Even a small auto body spray booth, a print shop, a backup generator, or a grain dryer usually needs a permit before it operates.
There are several permit types under the IEPA Air Permit Section:
- Construction Permit (pre-construction approval for new or modified equipment)
- Operating Permit (state operating permit for non-major sources)
- Joint Construction and Operating Permit (combined approval for smaller new sources)
- Lifetime Operating Permit (for very small, low-emitting sources)
- CAAPP Permit (the Clean Air Act Permit Program, Illinois’s version of federal Title V, for major sources)
- ROSS — Registration of Smaller Sources (a streamlined alternative to a full permit for sources under federally enforceable caps)
The current revision of the core application form is the APC-201-C series, and the IEPA prints the revision date in the lower corner of every page. Confirm you have the current revision before you file. Filing an outdated form is a top-ten reason for rejection.
Before You Start: Documents and Information You Need
Gather every document below before you open the form. Missing a single item often pushes your project back two months because the IEPA must restart its 90-day completeness clock under 35 Ill. Adm. Code 201.153.
- Federal Employer Identification Number (FEIN). The IEPA cross-checks this with the Illinois Secretary of State; a mismatch freezes your file.
- IEPA source ID number (if you already have one). Existing facilities have a 9-digit ID; using the wrong one routes your application to the wrong reviewer.
- Plot plan and process flow diagram. Required under 35 Ill. Adm. Code 201.152; without these, the IEPA cannot evaluate dispersion.
- Manufacturer specifications for every emission unit and control device. Stack height, exit velocity, exit temperature, and design capacity must come straight from the spec sheet.
- Safety Data Sheets (SDS) for every coating, solvent, fuel, or chemical used. VOC and HAP content drives your emissions math.
- Emission calculations with reference method. Use AP-42 emission factors, stack test results, mass balance, or manufacturer data — and cite which.
- Applicable requirements list. Identify every state rule (35 Ill. Adm. Code Parts 211, 212, 215, 216, 217, 218, 219), every NSPS (40 CFR Part 60) and NESHAP (40 CFR Parts 61 and 63) that applies.
- Compliance plan. A written description of how each emission unit will meet each applicable requirement.
- Fee payment. Construction Permit fees and CAAPP annual emission fees are set by 415 ILCS 5/9.6 and the IEPA fee schedule.
- Responsible Official’s name, title, and signature authority. Required under 35 Ill. Adm. Code 201.155 for CAAPP sources.
Where to Get the Form and How to Access It
Download every IEPA air permit application from the Illinois EPA Air Permit forms page. The forms are fillable PDFs with the IEPA logo and the form number printed in the upper right corner. The APC-201-C is the core Construction Permit application; the CAAPP application uses the APC-220 series; the ROSS uses the APC-300 series.
Do not use third-party copies. The IEPA updates the forms when 35 Ill. Adm. Code Part 201 changes, and the agency rejects superseded versions. The revision date is printed on the lower corner of each page.
You may also request paper copies by writing to the IEPA Bureau of Air at 1021 North Grand Avenue East, P.O. Box 19506, Springfield, IL 62794-9506, or by calling the Permit Section. Phone requests usually arrive in 5 to 10 business days. The IEPA does not charge for the forms themselves.
For electronic submission, the IEPA accepts applications through its online permit submission portal for many permit types. Larger CAAPP applications still travel by mail with hard copies because of the volume of attachments. Always keep a complete copy of everything you submit.
Step-by-Step: How to Fill Out the IEPA Air Pollution Permit Application Line by Line
The walkthrough below tracks the APC-201-C Construction Permit Application because it is the most-filed IEPA air form and shares its structure with the Operating Permit, the Joint Construction/Operating Permit, and the CAAPP application. Field names and box numbers come straight from the official form.
Section 1, Box 1 — Owner Name
This box asks for the legal name of the person or company that owns the source. Enter the exact legal name registered with the Illinois Secretary of State, in all capital letters, with no abbreviations.
For example, Maria Lopez Auto Body, Inc. writes MARIA LOPEZ AUTO BODY, INC. — not Maria Lopez ABI or Lopez Body Shop. Match the name on your most recent Illinois Annual Report.
If the owner is a sole proprietor with no LLC or corporation, enter the individual’s full legal name and add d/b/a with the trade name. A common mistake is entering the trade name only; the IEPA cannot serve enforcement notices on a name not registered with the state, and the application will be returned. A misconception filers carry is that the “owner” is whoever signs the lease — it is not. The owner is the legal entity that holds title to or controls the equipment.
Section 1, Box 2 — Operator Name
This box names the entity that will run the equipment day-to-day. If the owner and operator are the same, write SAME AS OWNER.
For example, Carlos Rivera leases space inside a larger industrial park and operates a printing press owned by the building’s holding company. He writes RIVERA PRINTING LLC in Box 2 and the holding company’s name in Box 1.
The nuance is that operator status carries direct compliance liability under 415 ILCS 5/9. A common mistake is leaving Box 2 blank when the operator differs from the owner, which voids the permit’s enforceability against the actual operator. The misconception is that listing both is “redundant” — it is not; it is the legal hook for inspections.
Section 1, Box 3 — Source Location (Physical Address)
The IEPA needs the physical street address where the equipment sits, not a P.O. Box. Enter street, city, county, and ZIP code. The county controls which IEPA regional office inspects the site.
For example, Aisha Patel’s dry cleaner sits at 412 W MAIN ST, URBANA, CHAMPAIGN COUNTY, IL 61801. She enters every line, including county, in capitals.
If the site has no street address yet (a greenfield project), give the section, township, and range, plus latitude and longitude in decimal degrees to four places. A frequent mistake is entering the corporate headquarters address instead of the actual emission site, which sends inspectors to the wrong building. The misconception is that GPS coordinates alone are enough; they are not — the IEPA needs both for new sites.
Section 1, Box 4 — Mailing Address
Use the address where you want every IEPA letter, draft permit, and notice to arrive. P.O. Boxes are allowed here.
For example, Marcus Bell, Plant Manager, lists his corporate office mailing address even though the boiler sits 40 miles away. He writes P.O. BOX 7700, PEORIA, IL 61601.
The nuance: if you list a personal address, you receive personal service of any enforcement notice. A common mistake is using an old address; missing a draft permit comment window means losing the right to challenge permit conditions. The misconception is that email replaces mail — IEPA still mails formal documents under 35 Ill. Adm. Code 201.156.
Section 1, Box 5 — FEIN and IEPA Source ID
Enter the 9-digit Federal Employer Identification Number from your IRS letter, then the 9-digit IEPA Source ID if you already have one. New sources leave the IEPA Source ID blank; the agency assigns one on first issuance.
For example, MARIA LOPEZ AUTO BODY, INC. writes 36-1234567 and leaves the Source ID blank because the spray booth is her first permitted unit.
The nuance: if you operate at multiple Illinois locations, each location gets its own Source ID. A common mistake is reusing a sister facility’s ID; this contaminates compliance history and the IEPA staff must manually unwind it. The misconception is that the Source ID is the same as the permit number — it is not; the Source ID stays with the site forever, the permit number changes with each issuance.
Section 2, Box 6 — SIC and NAICS Codes
The form requires both the 4-digit Standard Industrial Classification code and the 6-digit North American Industry Classification System code that best matches your primary activity.
For example, an auto body shop enters SIC 7532 and NAICS 811121. A commercial printer enters SIC 2752 and NAICS 323111.
Pull the codes from the Census NAICS lookup and the SIC manual. The nuance: if the facility has more than one process, list the code for the largest revenue source. A common mistake is guessing the code; the wrong NAICS routes the file to the wrong technical reviewer and adds weeks. The misconception is that NAICS does not matter for permitting — it does, because it drives applicable NSPS and NESHAP standards.
Section 3, Boxes 7–10 — Emission Unit Identification
Each piece of equipment that emits a regulated pollutant gets its own row. Enter the unit ID (you choose it, but be consistent), unit description, manufacturer, model, serial number, and date of manufacture or installation.
For example, Maria Lopez lists Unit ID: SB-01, Description: Downdraft Paint Spray Booth, Manufacturer: Global Finishing Solutions, Model: Ultra XD, Serial: GFS-2026-4412, Installed: 03/01/2026.
The nuance: number every unit, even insignificant ones, because the IEPA decides what is insignificant under 35 Ill. Adm. Code 201.210, not the filer. A common mistake is leaving out a small heater or solvent tank that “doesn’t really emit anything”; the omission is treated as a misrepresentation under 415 ILCS 5/44. The misconception is that grouping like units saves work — the IEPA usually requires each unit listed individually with its own ID.
Section 4, Boxes 11–16 — Process Description and Throughput
Describe the process in plain English, list every raw material, and give maximum hourly and annual throughput. Throughput drives every emission calculation, so be precise.
For example, Carlos Rivera’s offset printing press runs 4,000 lb/hr ink at maximum, 20,000,000 lb/yr. He writes those numbers exactly, with units.
The nuance: maximum throughput must equal the highest physically possible rate, not the rate you plan to operate at. Voluntary limits are taken in Section 8 (see below), not here. A common mistake is entering “design” throughput equal to “actual” throughput; if you ever exceed it, you are in violation. The misconception is that you can list “varies” — the IEPA rejects that and asks for the cap rating.
Section 5, Boxes 17–24 — Stack and Vent Parameters
For every stack or vent that releases pollution to the outside air, list height above ground (feet), inside diameter at the exit (feet), exit gas temperature (°F), exit gas velocity (feet per second), and flow rate (acfm). These feed the IEPA dispersion model.
For example, Marcus Bell’s boiler stack is Height: 60 ft, Diameter: 2.5 ft, Temp: 350 °F, Velocity: 35 ft/s, Flow: 10,300 acfm. He pulls every value from the boiler’s spec sheet.
The nuance: a horizontal vent or rain cap counts as zero vertical velocity for modeling, which dramatically increases predicted ground-level concentrations. A common mistake is rounding height to a whole number when the actual height is shorter; the IEPA verifies on inspection and a 2-foot overstatement can void modeling. The misconception is that “any stack will pass” — short stacks near taller buildings often fail downwash analysis under Appendix W.
Section 6, Boxes 25–32 — Control Equipment
List every control device — baghouse, scrubber, thermal oxidizer, condenser, carbon adsorber — with manufacturer, model, design capture and destruction efficiency, and the pollutant controlled.
For example, Aisha Patel’s perchloroethylene dry cleaner uses a refrigerated condenser, Columbia Boiler PCE-Cond, 95% control efficiency on PCE. She lists the manufacturer’s certification in the attachments.
The nuance: capture efficiency and destruction efficiency multiply. A 90% capture and 95% destruction yields only 85.5% overall control. A common mistake is using one number for both, which overstates control and triggers a Notice of Violation if a stack test shows true emissions. The misconception is that “control device” means only outlet equipment — capture hoods and ductwork count too under 35 Ill. Adm. Code Part 218.
Section 7, Boxes 33–40 — Emission Calculations
For every pollutant from every unit, show the calculation: emission factor × throughput × (1 − control efficiency) = emissions in pounds per hour and tons per year. Cite the source of the emission factor.
For example, Carlos Rivera writes VOC: 6.5 lb VOC/1,000 lb ink × 20,000,000 lb/yr ÷ 2,000 = 65 tons/yr uncontrolled, 6.5 tons/yr after 90% RTO. He cites AP-42 Section 4.9.1.
The nuance: HAPs must be calculated separately, both individually (10 tpy single HAP threshold) and combined (25 tpy aggregate). A common mistake is netting controls before showing uncontrolled emissions; the IEPA needs both numbers to confirm major source status under 35 Ill. Adm. Code 201.102. The misconception is that emission factors are conservative; many AP-42 factors are averages and a stack test may show higher emissions.
Section 8, Box 41 — Requested Federally Enforceable Limits (FESOP/Synthetic Minor)
If you want to stay below CAAPP/Title V major source thresholds (100 tpy criteria, 10 tpy single HAP, 25 tpy total HAP), request a federally enforceable limit here.
For example, Carlos Rivera requests a VOC cap of 24.0 tons per 12-month rolling total, with monthly recordkeeping, to remain a synthetic minor under 35 Ill. Adm. Code 201.146.
The nuance: the limit must be both practically enforceable (real recordkeeping) and below the threshold by a meaningful margin. A common mistake is requesting a cap exactly at 99.9 tpy; the IEPA almost always rejects that as not protective. The misconception is that synthetic minor status avoids all federal rules — it does not; NSPS and area-source NESHAP still apply.
Section 9, Boxes 42–50 — Applicable Requirements and Compliance Plan
For each emission unit, list every state rule, NSPS, NESHAP, and SIP requirement that applies, plus the method you will use to demonstrate compliance (continuous monitoring, periodic stack test, parametric monitoring, recordkeeping).
For example, Marcus Bell’s boiler triggers 40 CFR 60 Subpart Dc (NSPS for small industrial boilers) and 35 Ill. Adm. Code 212.123 (PM). He commits to annual fuel sulfur certification and monthly fuel use logs.
The nuance: missing an applicable requirement does not waive it — the rule still applies, but now you are out of compliance from day one. A common mistake is listing only state rules; federal NSPS and NESHAP are independent and the IEPA expects both. The misconception is that the IEPA will identify missing rules during review; reviewers may, but the legal duty to identify rests on the applicant.
Section 10, Box 51 — Responsible Official Certification and Signature
The Responsible Official signs and certifies, under penalty under 415 ILCS 5/44, that the application is true, accurate, and complete based on reasonable inquiry. The certification language is printed on the form; do not alter it.
For example, Janet Whitfield, Vice President of Operations, signs in blue ink, prints her name, title, phone, and email, and dates the signature 03/14/2026.
The nuance: only certain titles qualify as Responsible Official under 35 Ill. Adm. Code 201.155 — for a corporation, a President, Vice President, or higher; for a partnership, a general partner; for a sole proprietorship, the owner. A common mistake is having a consultant or environmental manager sign; the application is then legally unsigned and bounces. The misconception is that a digital signature always counts — the IEPA accepts wet ink for paper filings and a specific e-signature format for portal filings only.
Three Filled-Out Examples Using Real Scenarios
Scenario 1 — Maria Lopez, Auto Body Shop Adding a Spray Booth
Maria owns a small auto body shop in Urbana and is adding a single downdraft paint spray booth. She files an APC-201-C Construction Permit Application.
| Form Section | What Maria Enters |
|---|---|
| Box 1 Owner | MARIA LOPEZ AUTO BODY, INC. |
| Box 3 Location | 412 W MAIN ST, URBANA, CHAMPAIGN CO, IL 61801 |
| Box 5 FEIN | 36-1234567, Source ID blank (new) |
| Box 6 NAICS | 811121 |
| Box 7 Unit ID | SB-01, Downdraft Paint Spray Booth, GFS Ultra XD |
| Box 11 Throughput | 50 gal coating/week, 2,500 gal/yr maximum |
| Box 17 Stack | 18 ft height, 1.5 ft dia, 75 °F, 25 ft/s |
| Box 25 Control | Dry filter, 98% PM capture |
| Box 33 Emissions | VOC: 4.2 tpy; HAP: 0.8 tpy aggregate |
| Box 42 Applicable | 35 IAC 218.204 (VOC RACT), 40 CFR 63 Subpart HHHHHH (Area Source NESHAP) |
| Box 51 Signature | Maria Lopez, President, signed 03/14/2026 |
Scenario 2 — Carlos Rivera, Mid-Size Commercial Printer
Carlos operates a commercial offset printing plant in Peoria and is adding a heatset web press with a regenerative thermal oxidizer. He files a Joint Construction and Operating Permit Application and requests a synthetic minor VOC cap.
| Form Section | What Carlos Enters |
|---|---|
| Box 1 Owner | RIVERA PRINTING LLC |
| Box 3 Location | 2200 NE ADAMS ST, PEORIA, PEORIA CO, IL 61603 |
| Box 6 NAICS | 323111 |
| Box 7 Unit ID | PR-02, Heatset Web Offset Press, Goss Sunday 2000 |
| Box 11 Throughput | 4,000 lb ink/hr, 20,000,000 lb/yr |
| Box 25 Control | RTO, Durr Megtec, 98% VOC destruction |
| Box 33 Emissions | VOC uncontrolled 65 tpy, controlled 6.5 tpy |
| Box 41 Requested Limit | VOC ≤ 24 tpy, 12-month rolling, monthly logs |
| Box 42 Applicable | 35 IAC 218.401, 40 CFR 63 Subpart KK |
| Box 51 Signature | Carlos Rivera, Managing Member, 03/14/2026 |
Scenario 3 — Janet Whitfield, Major Source Renewing a CAAPP Permit
Janet is the Vice President of Operations at a coal-fired industrial steam plant in southern Illinois. The plant is a Title V major source and she is filing a CAAPP renewal using the APC-220 series.
| Form Section | What Janet Enters |
|---|---|
| Box 1 Owner | MIDWEST STEAM ENERGY, INC. |
| Box 3 Location | 900 RIVERSIDE RD, MARION, WILLIAMSON CO, IL 62959 |
| Box 5 IDs | FEIN 37-9988776, IEPA Source ID 199050AAH |
| Box 7 Units | BLR-01 through BLR-04, four 250 MMBtu/hr stoker boilers |
| Box 17 Stack | Common 200 ft stack, 8 ft dia, 320 °F, 55 ft/s |
| Box 25 Controls | ESP 99.5%, dry FGD 92% SO2, SNCR 30% NOx |
| Box 33 Emissions | PM 22 tpy, SO2 240 tpy, NOx 380 tpy, CO 95 tpy |
| Box 42 Applicable | 40 CFR 63 Subpart DDDDD (Boiler MACT), 35 IAC 214, CSAPR |
| Box 50 Compliance | CEMS for SO2/NOx/CO2, annual stack test for PM |
| Box 51 Signature | Janet Whitfield, VP Operations, 03/14/2026 |
How to File the Completed Form
Choose the channel that matches your application size and permit type. The IEPA accepts filings four ways, and each has its own fee, processing window, and proof requirements.
By Mail. Send the original signed application plus one copy and the fee check to Illinois EPA, Bureau of Air, Permit Section, 1021 North Grand Avenue East, P.O. Box 19506, Springfield, IL 62794-9506. Use certified mail with return receipt as proof of filing. The IEPA stamps the receipt date, which starts the 90-day completeness clock under 35 Ill. Adm. Code 201.153. Typical processing for a Construction Permit runs 90 to 180 days.
In Person. You may hand-deliver to the same Springfield address during business hours. The clerk stamps the receipt date on your copy. This is the fastest way to lock in a filing date when a deadline looms.
Electronic Submission. The IEPA’s air permit submission portal accepts most Construction Permits, Operating Permits, and ROSS registrations. You upload the signed PDF and pay the fee by ACH or credit card. The portal emails a confirmation with a tracking number — keep it as proof of filing. CAAPP applications still mostly travel by mail because of the size of attachments.
Fees. Construction Permit fees follow 415 ILCS 5/9.6 and depend on project type and project value, generally $500 to $5,000 for small sources and higher for major modifications. CAAPP sources also pay annual emission fees based on tons emitted. ROSS fees are flat and lower. Make checks payable to Illinois EPA. Accepted payment methods include check, money order, and (online) ACH or credit card.
What Happens After You File
The IEPA logs the application and sends an acknowledgment letter with the assigned application number within about two weeks. The letter restarts every clock if any item is missing.
A technical reviewer in the Permit Section then performs a completeness review. If the file is incomplete, you receive a deficiency letter listing missing items, and you must respond within 30 days under 35 Ill. Adm. Code 201.153. Once complete, the reviewer drafts permit conditions and runs dispersion modeling if the source is near a sensitive receptor.
For Construction Permits, the agency aims to issue or deny within 90 to 180 days. For CAAPP permits, federal law sets an 18-month issuance target from the complete-application date, with a public comment period of at least 30 days and EPA Region 5 review of 45 days. The draft permit is published on the IEPA public notice page and the public may submit comments and request a public hearing.
After issuance, the permit lists every applicable requirement, every emission limit, every monitoring obligation, and every recordkeeping and reporting deadline. You must operate within those conditions from day one. Annual emissions reports are due by May 1 of each year through the Annual Emissions Report system.
Mistakes to Avoid When Filling Out the Form
Each error below has stalled hundreds of Illinois air permit files. Treat the list as a pre-flight checklist.
- Using an outdated form. The IEPA rejects superseded versions and you start over.
- Mismatched legal name. A name that does not match the Illinois Secretary of State filing returns the application unprocessed.
- Wrong FEIN. Triggers a manual hold and weeks of back-and-forth.
- Skipping “insignificant” emission units. Treated as misrepresentation under 415 ILCS 5/44, with civil penalties up to $50,000 per violation.
- Listing only state applicable requirements. Missing federal NSPS or NESHAP makes the permit umbrella incomplete and exposes you to EPA enforcement.
- Netting control efficiency before showing uncontrolled emissions. Reviewers cannot confirm major source status and reject the file.
- Requesting a synthetic minor cap right at the threshold. The IEPA almost always denies; rebuild with a real margin.
- Wrong Responsible Official signature. A consultant or facility manager signature voids the certification.
- Missing process flow diagram or plot plan. Required by rule; the file is incomplete on arrival.
- Forgetting the fee or paying the wrong amount. The IEPA does not start review until payment clears.
- Using horizontal vents without disclosing them. Modeling fails on inspection and the permit may be reopened.
- Filing only the Construction Permit when a Joint Construction and Operating Permit is appropriate. You then need a second filing to operate, doubling the timeline.
Do’s and Don’ts
- Do download the form fresh from the IEPA forms page — revisions happen without notice.
- Do show your math for every emission calculation — reviewers must reproduce your numbers.
- Do list every applicable requirement, even ones you think do not apply — let the IEPA disagree on the record.
- Do request a pre-application meeting for complex projects — IEPA staff will flag fatal issues before you file.
- Do keep a complete, dated copy of everything you submit — you will need it during the public comment period.
- Do track the 90-day completeness clock yourself — do not rely on IEPA reminders.
- Don’t estimate stack parameters — pull every value from the manufacturer spec sheet.
- Don’t sign the application before the technical sections are final — late edits invalidate the certification.
- Don’t assume the trade name is the legal name — confirm with the Illinois Secretary of State.
- Don’t skip HAP calculations because you “are not a major source” — area-source NESHAPs still apply.
- Don’t use generic emission factors for a unique process — request approval to use a stack test or mass balance instead.
- Don’t mail the application without certified mail tracking — without a stamped receipt date, you cannot prove timely filing.
Pros and Cons of Filing on Your Own vs. With Help
| Filing on Your Own | Filing with a Consultant or Attorney |
|---|---|
| Saves $3,000–$25,000 in professional fees | Reduces rejection risk; experienced filers know reviewer preferences |
| Forces you to learn your own equipment and rules | Faster turnaround on emission calculations and applicable requirements analysis |
| Direct relationship with IEPA reviewers | Buffers technical disputes between the company and the agency |
| Best for ROSS and Lifetime Operating Permits | Best for CAAPP and major modifications under PSD/NSR rules |
| Risk of missing federal NSPS/NESHAP | Higher upfront cost, but lower lifetime compliance cost |
- Pro DIY: lower cost, deeper internal knowledge, simpler forms only.
- Pro DIY: direct line to the IEPA reviewer.
- Pro DIY: faster on truly small projects like a single backup generator.
- Con DIY: missed applicable requirements are common.
- Con DIY: the Responsible Official is personally on the line for any inaccuracy.
- Pro Consultant: experience with 35 Ill. Adm. Code nuances.
- Pro Consultant: professional dispersion modeling capability.
- Pro Consultant: template language the IEPA already accepts.
- Con Consultant: fees may exceed the project value for a tiny source.
- Con Consultant: the company still owns the certification and the violations.
Comparing Illinois Air Permit Types
| Permit Type | Best Fit |
|---|---|
| Construction Permit (APC-201-C) | Any new or modified emission unit, before construction starts |
| Operating Permit | Existing non-major sources after construction |
| Joint Construction & Operating | Smaller new sources where one filing covers both phases |
| Lifetime Operating Permit | Very small sources with stable, low emissions (e.g., small dry cleaners) |
| ROSS — Registration of Smaller Sources | Streamlined registration under federally enforceable cap |
| CAAPP (Title V, APC-220) | Major sources ≥100 tpy criteria, ≥10 tpy single HAP, or ≥25 tpy total HAP |
FAQs
Do I need a permit before I install equipment, or after?
Before. Illinois requires a Construction Permit before you begin installation under 35 Ill. Adm. Code 201.142. Starting work without one triggers daily civil penalties.
Can my consultant sign the application as the Responsible Official?
No. Only an officer, owner, or general partner with company-wide authority qualifies under 35 Ill. Adm. Code 201.155. A consultant signature voids the certification.
Do I list every emission unit, even tiny ones?
Yes. List every unit, including small heaters and tanks. The IEPA — not the filer — decides what counts as insignificant under Part 201.210.
In Box 3, do I write the corporate office address or the equipment site?
No to corporate office. Box 3 is the physical site where the equipment operates; Box 4 is the mailing address for IEPA correspondence.
Should I include both controlled and uncontrolled emissions in Box 33?
Yes. The IEPA needs uncontrolled, controlled, and post-limit emissions to confirm major source status and applicable rules.
Do I write maximum or actual throughput in Box 11?
Yes, write maximum physically possible throughput. Voluntary caps go in Box 41 as federally enforceable limits, not Box 11.
Are emission factors from AP-42 always acceptable?
Yes, AP-42 factors are accepted defaults, but the IEPA may require a stack test if AP-42 does not match your process or controls.
Do I need a separate permit for each piece of equipment?
No. One application can cover multiple units at one site. Each unit gets its own Section 3 row, but one permit issues.
Is electronic filing available for CAAPP applications?
No for most CAAPP renewals. The IEPA portal handles many smaller permits, but CAAPP usually still goes by mail because of attachment volume.
Will the IEPA fix calculation errors during review?
No. Reviewers flag errors in a deficiency letter, but the burden to recalculate and resubmit stays on the applicant under Part 201.153.
Do I need a public hearing for every permit?
No. Construction Permits rarely have hearings; CAAPP permits have a 30-day public comment period and a hearing only on request.
What is the penalty for operating without a permit?
Yes, there is one. 415 ILCS 5/42 authorizes civil penalties up to $50,000 per violation plus $10,000 per day of continuing violation.
Can I begin construction once I file, before the permit issues?
No. “Begin actual construction” before issuance is itself a violation under 35 Ill. Adm. Code 201.142, separate from operating without a permit.
Does a synthetic minor cap eliminate all federal rules?
No. Synthetic minor status avoids CAAPP/Title V, but federal NSPS and area-source NESHAPs still apply based on the activity itself.
Related reading
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- How to Fill Out Illinois IEPA NPDES Industrial Stormwater Permit + FAQs
- How to Fill Out Illinois IEPA Wastewater Treatment Permit (w/Examples) + FAQs
- How to Fill Out the Ohio EPA Air Permit-to-Install (with Examples) + FAQs
- How to Fill Out the Georgia EPD Air Quality Permit Application + FAQs
- How to Fill Out the Arizona ADEQ Air Quality Permit Application (Form 1) — With Examples + FAQs
- How to Fill Out the Washington Ecology Water Quality Modification Permit + FAQs