Instructions for Form 1045 (Application for Tentative Refund)
Last reviewed: 2025-10-24
Use the Form 1045-instructions: Instructions for Form 1045 (Application for Tentative Refund) Tax Form Calculator Form 1045-instructions: Instructions for Form 1045 (Application for Tentative Refund) as a stand alone tax form calculator to quickly calculate specific amounts for your 2026 1045 Instructions 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.
Beginning with the 2024 filing year, Form 1045-instructions no longer includes internal schedules or on-page computations. All calculations are now completed using the Form 1045 Calculator, which mirrors the current IRS layout and performs all required math automatically. These instructions exist solely to help you understand how and when to file, what to attach, and how to verify eligibility for a tentative refund.
When to file: Generally within one year after the end of the tax year in which the loss or credit arose. File Form 1045-instructions only after submitting the corresponding income tax return. Where to file: The IRS Service Center listed for your location. What to attach: copies of prior-year returns and all schedules reflecting refigured amounts in the carryback years. We recommend computing and printing your completed form directly from the online calculator for accuracy.
Key update: The IRS eliminated Schedules A and B from Form 1045 and transferred all NOL computations to Form 172. Form 1045 now functions as a summary application only. To determine carryback adjustments, generate your figures using the Form 1045 Calculator before filing. Retain all supporting schedules, Forms 172, 3800, 6781, and 6251 (if applicable) with your submission.
Last reviewed: 2025-10-24: If you believe this form requires an update, please contact us.
Purpose of these Instructions
This page provides general guidance on completing and filing Form 1045 – it does not perform or display computations. To calculate your tentative refund accurately, use the dedicated interactive Form 1045 Calculator. Once your figures are finalized, attach the generated form and required schedules when submitting your claim. Review the official IRS instructions for details on qualifying events, timing, and processing expectations (generally 90 days).
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.
Important Notes
All calculations are estimates for guidance only. Always review your return and consider professional advice when submitting official filings.