Unfiled tax returns: how to catch up on back taxes

There is no cutoff for filing. The IRS says you can file a return for any prior year, and its policy is to accept every delinquent return a taxpayer sends in.

Refunds are different. If you are due a refund of withholding or estimated tax, or a credit such as the Earned Income Tax Credit, you have to file within three years of the return’s due date to claim it; after that, the money becomes the property of the U.S. Treasury. In March 2026 the IRS said more than 1.3 million people had until April 15, 2026 to claim their refunds for 2022.

A refund that is still in time can be held: the IRS holds refunds when its records show one or more of your returns are past due, until it gets them or an acceptable reason for not filing. And a refund is applied to tax you still owe the IRS or a state tax agency, and can go to unpaid child support or other past-due federal debts such as student loans.

How far back you should file is a separate question from how far back you can. The IRS’s policy statement on delinquent returns says that, normally, it enforces filing for no more than six years. Going further back, or enforcing fewer than six, needs a manager’s approval.

This is policy, not a statute of limitations. The IRS decides case by case, weighing things like your history of not filing, the tax likely to be due and the effect on voluntary compliance, so it can ask for more years or fewer.

If you are not sure you even had to file for a given year, the answer is in the “Do You Have To File?” section of that year’s Form 1040 instructions.

If you do not file, the IRS may file a substitute return for you, and it might not give you credit for the deductions and exemptions you are entitled to. It then sends a Notice of Deficiency, CP3219N, also called a 90-day letter: you have 90 days to file your own return or petition the Tax Court, and if you do neither, the IRS assesses the tax it proposed. Once you have that notice, you cannot get an extension to file.

The resulting bill, if unpaid, goes to collection, which can mean a levy on your wages or bank account or a notice of federal tax lien, and repeated failure to file can bring further penalties or criminal prosecution. The usual three-year limit on the IRS assessing more tax does not begin with a substitute return. It begins when you file your own.

Even after a substitute return, the IRS says filing your own is still in your best interest, so the exemptions, credits and deductions you are entitled to are counted. It will generally adjust your account to the correct figures.

Two penalties apply when tax is owed. The failure-to-file penalty is 5% of the unpaid tax for each month or part of a month the return is late, up to 25%. The failure-to-pay penalty is 0.5% of the unpaid tax for each month or part of a month it stays unpaid, also up to 25%. In a month when both apply, the filing penalty is reduced by the payment penalty; after five months the filing penalty is at its maximum, but the payment penalty continues.

A return more than 60 days late also has a minimum failure-to-file penalty: a set dollar amount or 100% of the unpaid tax, whichever is less. The dollar amount depends on when the return was due; for a 2025 return, due in April 2026, it is $525. Both penalties are figured on the tax left after on-time withholding, estimated payments and refundable credits, so a return that shows a refund has no failure-to-file penalty.

Interest comes on top. It runs from the original due date until the balance is paid in full, accrues daily on unpaid tax, penalties and interest, and its rate can change every quarter. An extension of time to file does not stop it.

Start with what the IRS already has. A wage and income transcript shows the information returns the IRS received for you, such as Forms W-2, 1099, 1098 and 5498, for the current year and nine prior years. You can view and download it in your IRS Online Account, or request it on Form 4506-T by checking the box on line 8, which can take several weeks. It only shows forms filed with the IRS, which may not be every form issued to you, so fill the gaps from your own records and from the payers.

Each year then goes on its own year’s Form 1040, with that year’s instructions, which the IRS keeps with its prior-year forms on IRS.gov. Only recent years can be e-filed: the IRS e-file system accepts the current tax year and the two before it, which during 2026 means 2025, 2024 and 2023. Older returns go on paper.

Send a past-due return the same way, and to the same place, as an on-time one, unless you have an IRS notice; then it goes to the address on the notice. The IRS says an accurately completed past-due return takes about six weeks to process.

File every return that is due, even if you cannot pay it all: the failure-to-file penalty is the larger of the two, and filing stops it from building. Then pay what you can, as soon as you can, from a bank account through IRS Direct Pay or your IRS Online Account, by check or money order, or by card, where a processing fee applies.

If you cannot pay in full, the IRS has two kinds of payment plan. A short-term plan gives you up to 180 days to pay the balance; a long-term plan, also called an installment agreement, spreads it into monthly payments. An individual can apply online for a short-term plan when they owe less than $100,000 in combined tax, penalties and interest, and for a long-term plan when they owe $50,000 or less and have filed all required returns. Setup fees depend on the plan and how you apply, and the IRS lists them on its payment plan page.

Penalties and interest keep accruing while a plan runs, and the reduced late-payment rate during a plan, 0.25% a month, applies only to returns that were filed on time. While a plan request is being considered or a plan is in effect, the IRS generally does not take enforced collection action.

The IRS has an administrative waiver, First Time Abate, for failure-to-file and failure-to-pay penalties. It depends on your history: the same type of return filed on time for the three prior years, and no penalties in that period other than an estimated tax penalty, or ones later removed for reasonable cause or IRS error. You have to ask for it, by phone or in writing.

For 2025 and later returns, the IRS is moving to an automatic version starting in summer 2026, the Automatic Exemption from Penalty: if your returns were filed and your tax paid on time for the three prior years, the late-filing and late-payment penalties are not assessed at all. Outside those, a penalty may be reduced or removed for reasonable cause, if you acted in good faith and circumstances beyond your control kept you from complying. If you have a reasonable explanation for filing late, the IRS asks you to include it with the return.

None of this is promised. Both tests look at the years before the penalty year, so a run of unfiled years usually leaves the later ones without the history they ask for. And interest on the tax itself stays: the IRS does not remove interest for reasonable cause or first-time relief, though interest on a penalty goes when the penalty does.