If you received advance premium tax credit (APTC) through the Health Insurance Marketplace and you don’t file Form 1095-A information with your return, the IRS freezes your refund and sends you a letter demanding it. What happens if you don’t file Form 1095-A depends entirely on what you do next: respond within 20 days and you finish reconciliation like anyone else; ignore the letter and the IRS assumes you must repay every dollar of subsidy you received during the year, then adds penalties and interest on top.
Form 1095-A itself isn’t filed with your return. It’s the statement the Marketplace sends you each year, and its numbers feed Form 8962, the reconciliation form the IRS actually expects.1Internal Revenue Service. About Form 1095-A, Health Insurance Marketplace Statement When people say they “didn’t file their 1095-A,” they usually mean they left Form 8962 off their return. The consequences below are the same either way.
The IRS Freezes Your Return and Sends Letter 12C
The Marketplace reports advance payments directly to the IRS, so the agency already knows whether APTC was paid on your behalf. If your return arrives without Form 8962, processing stops and any refund is held. You receive Letter 12C (also written as Letter 0012C), which tells you the Marketplace reported advance payments and your return is missing the reconciliation.2Internal Revenue Service. Reconciling Your Advance Payments of the Premium Tax Credit
You have 20 days to respond with a completed Form 8962 and a copy of your Form 1095-A.3Internal Revenue Service. Understanding Your Letter 12C That is a tight window if you don’t already have your 1095-A in hand.
If you miss the deadline, the IRS assumes the worst-case answer: that you weren’t eligible for any premium tax credit and must repay every dollar of APTC that was paid on your behalf. Most people who received APTC actually qualify for at least some of it, so that default almost always overstates what you owe. The IRS won’t figure the smaller number for you. Reversing the default requires submitting the forms you should have sent in the first place.
Once the default balance is assessed, the failure-to-pay penalty runs at 0.5% of the unpaid amount per month, capped at 25%.4Internal Revenue Service. Failure to Pay Penalty Interest compounds daily at 7% per year as of the first quarter of 2026.5Internal Revenue Service. Interest Rates Remain the Same for the First Quarter of 2026 On a $4,000 default assessment, penalty and interest can add hundreds of dollars within a few months.
Repayment Caps Are Gone Starting in 2026
Before 2026, taxpayers with household income under 400% of the federal poverty line had a cushion. Excess APTC repayment was capped based on income and filing status, with limits ranging from $375 to $3,250. A single filer under 200% of the poverty line, for example, owed back no more than $375 for the 2025 tax year, no matter how large the excess.
Section 71305 of Public Law 119-21 eliminated those limits for tax years beginning after December 31, 2025.6Office of the Law Revision Counsel. 26 USC 36B – Refundable Credit for Coverage Under a Qualified Health Plan For 2026 and later, if reconciliation shows you received more APTC than you qualified for, you repay the full excess regardless of income. A default assessment triggered by ignoring Letter 12C in this environment is far more punishing than under the old rules, because there is no ceiling to fall back on.
You Can Lose Future Marketplace Subsidies
The cost isn’t limited to the tax year you skipped. If you fail to file and reconcile for two consecutive years, the Marketplace will determine you ineligible for advance premium tax credits going forward. You can still buy a Marketplace plan, but you’ll pay the full unsubsidized premium until you go back and reconcile the missing years.7Centers for Medicare & Medicaid Services. Failure to File and Reconcile (FTR) Operations FAQ
Even one year of non-compliance puts your account on notice. The Marketplace flags it with a one-year failure-to-reconcile status, and if you don’t fix things before the next open enrollment period, subsidies for the following plan year are at risk.8HealthCare.gov. How to Reconcile Your Premium Tax Credit For households whose APTC covers a large share of the monthly premium, that loss can make coverage unaffordable.
How to Respond to Letter 12C
You do not file an amended return in response to Letter 12C. The IRS instructs taxpayers not to submit Form 1040-X in this situation. Instead, you send the completed Form 8962 and a copy of your Form 1095-A, and the IRS uses them to finish processing your original return.2Internal Revenue Service. Reconciling Your Advance Payments of the Premium Tax Credit
Three ways to send it:
- Fax to the number printed on your letter. Fastest option, and an online fax service works.
- Upload PDFs, JPGs, or PNGs through the IRS Document Upload Tool.9Internal Revenue Service. IRS Document Upload Tool
- Mail to the address on the letter. Slowest; factor delivery time into the 20-day window.
If you think the letter is wrong because you didn’t enroll through the Marketplace or didn’t receive APTC, respond anyway with a written explanation. Silence produces the default assessment; a response, even a disputing one, keeps your file open.
How to Get a Missing or Corrected 1095-A Fast
The Marketplace is required to send Form 1095-A by mid-February, but if yours never arrived or got lost, the fastest replacement is your online account at HealthCare.gov or your state exchange. Log in, open the tax documents section, and download the form.2Internal Revenue Service. Reconciling Your Advance Payments of the Premium Tax Credit If you can’t get into your account, call the Marketplace Call Center at 1-800-318-2596; a mailed copy typically takes seven to ten business days, so treat this as a last resort against the 20-day clock.
If the numbers on your 1095-A look wrong, call the Marketplace to request a correction.10Centers for Medicare & Medicaid Services. How Can I Help My Clients Make Corrections to Their Form 1095-A Demographic errors like a misspelled name or wrong Social Security number don’t require a corrected form; you can just enter the right information on your return. Financial errors do require a correction before you complete Form 8962. If a voided 1095-A shows up, don’t use it or the original to claim any premium tax credit.11Internal Revenue Service. Corrected, Incorrect or Voided Form 1095-A
When You Actually Need an Amended Return
Form 1040-X only enters the picture in specific situations, none of which is a response to Letter 12C. You need an amended return if the IRS already fully processed your original return before the missing 8962 was caught, if a corrected or voided 1095-A arrives after you filed and the new numbers change your tax, or if you made other premium tax credit errors on the original.11Internal Revenue Service. Corrected, Incorrect or Voided Form 1095-A
An e-filed original can be amended electronically for the current or two prior tax years using tax software; a paper original must be amended on paper.12Internal Revenue Service. File an Amended Return Attach the completed Form 8962 and a copy of your 1095-A either way. Processing generally takes 8 to 12 weeks and can stretch to 16.13Internal Revenue Service. Where’s My Amended Return
One Boundary Worth Knowing
If you didn’t receive any advance premium tax credit during the year and aren’t claiming the credit at tax time, you don’t need to file Form 8962 at all, and a missing 1095-A doesn’t create the problem described here.14HealthCare.gov. How to Use Form 1095-A The reconciliation requirement applies to anyone for whom APTC was paid, even those who wouldn’t otherwise have to file a return.15Internal Revenue Service. Form 1095-A, Health Insurance Marketplace Statement If APTC hit your Marketplace account during the year, the IRS is expecting Form 8962 with your return, and skipping it starts the sequence at the top of this page.