How to Actually File the Chronic-Leaker Report With the EPA — CDX, HAWK, Form 3520-36, and the 12 Fields Due March 1

You know the number. If a system with 15 or more pounds of charge takes on 125% or more of its full charge in refrigerant additions within one calendar year, it's a chronic leaker, and the EPA requires a report by March 1 of the following year. We covered what the 125% rule is and how the math works when the rule took effect, and how to watch your running totals before summer pushes a marginal system over.

But there's a question those posts — and honestly, most of the trade coverage — leave hanging:

Report it where? To whom? On what form? Through what door?

"Submit a report to the EPA" sounds like something that might happen by email, or a PDF on letterhead, or a certified letter to a regional office. It is none of those. It's an electronic filing through a specific federal reporting platform, on a specific EPA form, with twelve specific data fields and an officer's signature. And with the first March 1 deadline ever landing on March 1, 2027 — for calendar-year 2026 exceedances that are accumulating on rooftops right now — this is the year to learn the actual mechanics.

What Triggers the Report (One More Time, Precisely)

The obligation lives in § 84.106(j), and it's one sentence:

Three details in that sentence do real work:

• "125 percent or more." Hitting 125.0% exactly triggers the report. This isn't a threshold you have to exceed — you have to stay under it.
• "In a calendar year." January 1 to December 31. This is not the leak-rate math — no annualizing, no rolling window. It's a straight sum of pounds added against the full charge. A 100-lb system that took 45 lbs in March, 40 in July, and 40 in October is at 125% on the October top-off.
• "Must submit a report... by March 1 of the subsequent year." The deadline is fixed. It doesn't float from the exceedance date, and repairing the system afterward — even a repair that passes its verification test — doesn't cancel it. The report looks backward at the calendar year the system actually had.

The Door You File Through: CDX → HAWK

Start with the sentence that rules out every informal channel. § 84.106(m) opens:

No paper. No email. The "applicable reporting platform" for leak-repair reporting is EPA's HAWK reporting system, and you reach it through the Central Data Exchange — CDX, the agency's front door for electronic reporting at cdx.epa.gov. Per EPA's ER&R reporting resources page, owners and operators submitting a leak report register in CDX as a "Leak Reporter" to get HAWK access.

The report itself goes in on an EPA-published, Excel-based form: the HFC Chronic Leak Report, EPA Form 3520-36. HAWK is the same door used for the other Subpart C leak-repair filings you may already know from the repair-deadline extension — extension requests (Form 3520-38), retrofit/retirement relief and schedule extensions (3520-41 and 3520-42), and purged-refrigerant notifications (3520-39) all travel the same route. EPA's support contact for the program is HFCEmissionsReductions@epa.gov, and the agency publishes a Leak Reporting User Guide walking through registration and submission.

Two practical warnings from everyone who has ever dealt with CDX:

Register early. CDX registration is an identity-verification process, not a checkout flow. If a customer's system finished 2026 over 125%, get the CDX account and Leak Reporter role sorted in January — not on February 26.

Know whose filing it is. The § 84.106(j) duty sits on the owner or operator of the appliance, not the servicing contractor — the same split we walked through in who the EPA actually fines under Subpart C. But look at the twelve required fields below and ask who actually holds that data. It's the contractor. A shop that can hand its customer a complete, filing-ready data package in January is doing the thing that makes service agreements renew themselves.

The Twelve Fields of § 84.106(m)(4)

Here's the full required contents of the report, straight from § 84.106(m)(4) — every item the form has to carry:

1. Basic identification information — owner or operator, facility name, facility address where the appliance is located, and the appliance ID or description
2. Appliance type — comfort cooling or other, industrial process refrigeration, or commercial refrigeration
3. Refrigerant type
4. Full charge of the appliance (pounds)
5. Annual percent refrigerant loss
6. Dates of refrigerant addition
7. Amounts of refrigerant added
8. Date of the last successful follow-up verification test
9. Explanation of cause of refrigerant losses
10. Description of repair actions taken
11. Whether a retrofit or retirement plan has been developed for the appliance — and if so, the anticipated date of retrofit or retirement
12. A signed statement from an authorized company official

Read that list the way an inspector would. Items 1 through 7 are the appliance file you should already be keeping — identity, category, refrigerant, full charge, and the complete addition history for the year. If your records are in order, they're a transcription job.

Items 8 through 11 are where February gets ugly for shops that documented casually.

Item 8 — the last successful follow-up verification test. If the system tripped a threshold during the year (and at 125%, it almost certainly did), each repair had to be proven with initial and follow-up verification tests under § 84.106(e). The report asks for the date of the last successful one. If verification tests happened but nobody wrote down which ones passed and when, you're reconstructing that from memory in front of a federal form.

Item 9 — explanation of cause. Why did this system lose 125% of its charge? "It leaks" is not an explanation. A real answer names the failure: corroded evaporator coil replaced in June, recurring Schrader-valve seepage, vibration cracking at a braze joint that took three visits to isolate. The only way that answer exists in February is if the tech's leak-location and cause notes were captured on each ticket at the time — which is exactly the documentation habit the field-by-field service-ticket teardown exists to build.

Item 10 — repair actions taken. Every repair, not vibes. Dates, components, outcomes.

Item 11 — the retrofit-or-retire question. The form makes the owner state, on the record, whether a retrofit or retirement plan exists for this system and when it lands. A chronic leaker that's had repeated failed repairs may already be legally obligated to have one — this field is the EPA checking that the two provisions line up.

Item 12 — the signature. Like the extension request, this carries a signed statement from an authorized company official. It's an attestation, with a name on it, that the contents are true. Treat it with permit-application weight.

The report is a transcription job for a shop with real per-appliance records — and an archaeology dig for a shop without them. Which one you are gets decided in July, not February.

The Timeline, Concretely

For a system that crosses 125% during 2026:

One more nuance worth naming: filing the report is not a penalty and not an admission of a violation. A system can leak 125% in a year with every repair made on time, every verification test passed, and every record clean — the report is a disclosure, not a citation. What turns a chronic leaker into an enforcement problem is the other trail: missed repair deadlines, absent verification tests, no records. The report just makes sure the EPA knows which systems to ask about.

Make It a Non-Event

The March 1 filing is the single most predictable obligation in Subpart C — you can see it coming from months away, because the number that triggers it accumulates one service ticket at a time. The shops that will handle the first deadline cleanly are doing three things this summer:

Tracking cumulative additions per appliance, per calendar year. Not per visit — per system, running total, against full charge. That's the trigger number, and watching it mid-year is what turns February surprises into July conversations.

Capturing cause and repair notes on every ticket. Fields 9 and 10 can't be reconstructed later. Thirty seconds of "found leak at king valve packing, repaired, follow-up verification passed 6/14" per ticket is the whole cost.

Deciding the retrofit/retire question before the form asks. If a system is going to finish the year over 125%, the owner conversation about field 11 should happen when the total crosses 100% — while there's still time to develop a plan deliberately instead of confessing "no plan" on a federal form.

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The filing is the last step of a chain that starts with the running total. If you haven't read it yet, start with the 125% rule itself — what counts toward the total, what doesn't, and how the calendar-year math differs from the leak-rate methods.