Form 1045: Application for Tentative Refund, Filing and Deadline

Form 1045, the Application for Tentative Refund, is the IRS form individuals, estates, and trusts use to get a fast refund when a current-year loss or credit can be carried back to an earlier year. The IRS must act on the application within 90 days, which is dramatically quicker than the months or more it takes to process an amended return. The catch is in the name: the refund is tentative, and the IRS can audit later and take it back with interest if the numbers don’t hold up.¹

Who Can File It

Form 1045 is for individuals filing Form 1040 and for estates and trusts filing Form 1041.¹ Corporations cannot use it. C corporations and other corporate filers use Form 1139 instead, which serves the same tentative-refund function but is built around corporate carrybacks such as net capital losses.²

What Qualifies for a Carryback

You can only file Form 1045 if you have one of four specific items the law allows to be applied against a prior year’s tax.¹

Net Operating Losses

A net operating loss (NOL) arises when your allowable business deductions exceed your gross income. Under current law, most NOLs cannot be carried back at all. They carry forward indefinitely, with the deduction in any future year capped at 80% of that year’s taxable income figured without the NOL.³

The main exception is farming losses, which can still be carried back two years.³ That exception is why farming losses are one of the more common reasons individuals actually file Form 1045 today.

Net Section 1256 Contract Losses

Section 1256 contracts include regulated futures contracts, foreign currency contracts, and certain options. An individual with a net loss on these contracts can elect to carry it back three years, but only against gains from section 1256 contracts in those prior years.⁴ Corporations, estates, and trusts cannot make this election. Individuals claim it by filing Form 1045 (or an amended return) with an amended Form 6781.

Unused General Business Credits

The general business credit reported on Form 3800 has a mandatory one-year carryback. If total business credits exceed your tax liability, the unused portion goes back one year first, then forward for up to 20 years.⁵ Form 1045 is the fast-track way to collect the refund that carryback generates.

Claim of Right Adjustments

A claim of right situation happens when you reported income in a prior year, paid tax on it, and later had to repay it. If the repayment exceeds $3,000, Section 1341 lets you either deduct the repayment in the current year or take a credit equal to the extra tax you paid in the prior year, whichever produces the lower tax.⁶ If the credit method wins and creates an overpayment, Form 1045 can be used to recover it quickly.⁷

The One-Year Filing Deadline

Form 1045 must be filed within one year after the end of the tax year in which the loss, unused credit, or claim of right adjustment arose.⁸ For a calendar-year taxpayer with a qualifying 2025 loss, the deadline is December 31, 2026. It cannot be extended.

Missing that window doesn’t kill the refund. You can still file Form 1040-X (or an amended Form 1041), which must generally be filed within three years after the due date, including extensions, of the return for the year the loss or unused credit arose.⁹ The refund amount is the same. You just wait a lot longer for it.

Preparing the Application

Form 1045 involves a two-step calculation, and this is where most of the work sits.

Schedule A converts the loss shown on your tax return into the statutory NOL amount. The two are rarely identical, because the code requires specific adjustments such as removing non-business deductions in excess of non-business income and adding back certain exclusions.¹ The resulting figure is your actual NOL, which may be larger or smaller than the loss on the return.

Schedule B then recomputes the tax for each carryback year as if the NOL deduction or other carryback item had been claimed on the original return.¹ That means recalculating adjusted gross income, taxable income, and any credits that depend on income levels. The difference between the tax originally paid and the recomputed tax is your tentative refund.

Document every calculation clearly and attach copies of the returns for the carryback years with any supporting schedules. The IRS relies on your figures to issue the refund; a sloppy application invites rejection.

How to Submit It

The IRS now accepts Form 1045 electronically. If you e-file, you’ll also complete Form 8453-TR, the e-file declaration and authorization for the application.¹⁰ Paper filing is still an option, mailed to the IRS service center for the area where you live using the addresses in the form instructions.⁸

How the IRS Processes the Application

The IRS must act on Form 1045 within 90 days. The clock starts on the later of the date the complete application is filed or the last day of the month containing the due date (with extensions) for the return for the loss year.¹¹ So filing in March when the return isn’t due until April 15 means the 90 days start running in April.

The review during this window is limited. The IRS checks for math errors and material omissions but essentially accepts your figures at face value. Three outcomes are possible: the full refund is issued, a partial refund is issued after correcting minor errors, or the application is disallowed for uncorrectable errors or material omissions.

A disallowance is not appealable in court. But it also doesn’t cost you the underlying refund. You can still file Form 1040-X before the statute of limitations expires and pursue the same claim through the standard amended-return process.⁷

What “Tentative” Actually Costs You

Getting the refund isn’t the end of the matter. The IRS keeps the right to fully examine both the loss year return and the carryback year returns long after the money has been deposited. If a later audit finds the carryback was overstated or miscalculated, you owe back the excess plus interest, compounded daily from the date the tentative refund was issued.¹²

On top of interest, Section 6676 authorizes a 20% penalty on the “excessive amount” of a refund claim, meaning the portion you weren’t actually entitled to.¹³ The penalty doesn’t apply if you can show reasonable cause, which the IRS evaluates based on the complexity of the issue, your level of sophistication, and whether you exercised ordinary care in preparing the claim. It also doesn’t stack with accuracy-related or fraud penalties on the same amount.¹⁴

Form 1045 is built for speed, not for testing aggressive positions. When there’s genuine uncertainty about whether a loss qualifies or how large it is, Form 1040-X is the safer route. It takes longer, but it doesn’t carry the same expectation of rapid processing at face value, and it doesn’t put you on the clock for interest running from an early refund date.

1
Internal Revenue Service. About Form 1045, Application for Tentative Refund
2
Internal Revenue Service. About Form 1139, Corporation Application for Tentative Refund
3
Office of the Law Revision Counsel. 26 US Code 172 – Net Operating Loss Deduction
4
Office of the Law Revision Counsel. 26 USC 1212 – Capital Loss Carrybacks and Carryovers
5
Office of the Law Revision Counsel. 26 USC 39 – Carryback and Carryforward of Unused Credits
6
Internal Revenue Service. IRM 21.6.6 Specific Claims and Other Issues
7
Internal Revenue Service. Instructions for Form 1045
8
Internal Revenue Service. Instructions for Form 1045
9
Internal Revenue Service. Instructions for Form 1040-X
10
Internal Revenue Service. About Form 8453-TR, E-file Declaration or Authorization for Form 1045/1139
11
Office of the Law Revision Counsel. 26 USC 6411 – Tentative Carryback and Refund Adjustments
12
Internal Revenue Service. Internal Revenue Bulletin 2026-8
13
Office of the Law Revision Counsel. 26 USC 6676 – Erroneous Claim for Refund or Credit
14
Internal Revenue Service. Erroneous Claim for Refund or Credit Penalty