Application for Tentative Refund

Last reviewed: 2025-10-24

Use the Form 1045: Application for Tentative Refund Tax Form Calculator Form 1045: Application for Tentative Refund as a stand alone tax form calculator to quickly calculate specific amounts for your 2026 1045 state tax return. Alternatively, you can use one of our Combined Federal and State Tax Estimators to quickly calculate your salary, tax, and take-home pay.

Use this tool to prepare Form 1045 to request a tentative refund from carrybacks (NOL, unused general business credit, net section 1256 contracts loss) or a claim of right adjustment. Enter amounts from prior-year returns and supporting schedules to compute the tentative decrease in tax.

Tip: For tax years 2026 and later, compute any NOL on Form 172 and enter those results on Form 1045. Schedules A and B were removed from Form 1045 beginning with 2024; only summary figures belong on this form. We round calculated totals to two decimals.

Application for Tentative Refund
1 This application is filed to carry back: a Net operating loss (Form 172) $ b Unused general business credit $ c Net section 1256 contracts loss $
2a	For the calendar year 2026, or other tax year beginning and ending		2b	Date tax return was filed
3	If unused credit created by another carryback, enter year of first carryback
4	If you filed joint/separate returns for some years involved, list years and J/S
5	If SSN for carryback year differs, enter SSN and year(s)
6	If you changed accounting period, enter date permission granted
7	Have you filed a petition in Tax Court for the year(s) to which the carryback is applied?
8	Is any part of the decrease due to a reportable transaction (Form 8886)?
9	Did an NOL or net sec. 1256 loss cause release of foreign tax credits or other credits?
Computation of Decrease in Tax (three preceding tax years)
	1st preceding year		2nd preceding year		3rd preceding year
	Before	After	Before	After	Before / After
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33	Overpayment of tax due to claim of right adjustment under section 1341(b)(1) (attach computation) $

Reminder: File Form 1045 after you file the corresponding income tax return for the loss/credit year. Most carryback claims have strict timing rules. Keep copies of supporting Forms 172, 3800, 6781, and prior-year returns with your application.

Last reviewed: 2025-10-24: If you believe this form requires an update, please contact us.

About Form 1045

Form 1045 provides a faster way to receive a refund related to carrybacks or claim of right adjustments. NOL amounts are now computed on Form 172. See current IRS instructions for eligibility, deadlines, and where to file.

Frequently Asked Questions

Can I estimate the General Business Credit?

Start with Form 3800 and then reflect the credit here.

How much would a 401(k) contribution change my net?

Model it with the 401(k) Calculator then rerun this page with your pre-tax amount.

Considering an IRS Offer in Compromise?

Read through Form 656-B to understand eligibility and steps.

What does FICA include?

FICA includes Social Security and Medicare payroll taxes withheld from employee wages.

Is there a quick pay-frequency comparison?

Yes—switch frequency on this page; for employer filings see 941 vs 944.

Important Notes

All calculations are estimates for guidance only. Always review your return and consider professional advice when submitting official filings.