43: Part-Year Resident & Nonresident Income Tax Return 2025 (2025)
Idaho · Idaho Tax Commission · Used for tax years 2025
Idaho Form 43 is the 2025 Part-year Resident and Nonresident Income Tax Return. It reports Idaho income, adjustments, deductions, taxes, credits, withholding, and payments, and includes a comparison of federal and Idaho adjusted income.
Who files this form
Form 43 is Idaho’s 2025 income tax return for part-year residents and nonresidents. The supplied text does not include the general income thresholds that determine whether you must file.
- Use Form 43 if one spouse is an Idaho resident and the other is not, and you filed a joint federal return.
- An Idaho resident on active military duty must use Form 40 unless their spouse is a part-year resident or nonresident.
- Nonresident aliens for federal tax purposes are also nonresidents for Idaho income tax purposes.
You may also use Form 43 to claim a Food Tax Credit refund for yourself if you were an Idaho resident during the tax year, Idaho does not require you to file an income tax return, and your spouse was a part-year resident or nonresident.
What you'll need
Complete your federal income tax return before starting Form 43. Include a complete copy with your Idaho return, unless you are not required to file and are filing Form 43 only for a Food Tax Credit refund.
Have these items ready, as applicable:
- Your identifying information, your spouse’s information, and each dependent’s name, Social Security number and birthdate.
- Forms W-2 and any Forms 1099 showing Idaho withholding.
- Federal schedules supporting reported income, such as Schedule C or C-EZ, Schedule D if required, Schedule E, Schedule F, and Form 4797.
- Federal Schedule A if you claim itemized deductions.
- Form 39NR for applicable additions, subtractions and credits, or to list more than four dependents.
- The other state’s income tax return and Form 39NR if claiming a credit for income tax paid to that state.
- Forms 44, 75, 49ER and Idaho K-1s when required by the lines you complete.
- Idaho Form 402 if you are a nonresident apportioning income from a business or farm operating in Idaho and another state.
- Federal Form 8332 or a copy of the court order if you are a noncustodial parent claiming a dependent.
Include a schedule or explanation if line 7 wages do not match the Idaho income amounts on your W-2s. Include your calculations for deductions claimed on line 25.
How to file
- Complete your federal return first, then use it to complete Form 43 and the applicable schedules.
- Select your filing status and residency status. On a joint return, select a residency status for each spouse.
- Include the required supporting documents. Do not staple the return.
- Sign the return. Both spouses must sign a joint return.
Mail a return with payment to:
Idaho State Tax Commission
PO Box 83784
Boise, ID 83707-3784
Mail a return without payment to:
Idaho State Tax Commission
PO Box 56
Boise, ID 83756-0056
The form allows you to pay online or make a check payable to the Idaho State Tax Commission. The supplied text does not provide e-file instructions.
Common mistakes
- Incorrect identification numbers: Check that your return and W-2s show the correct SSN or ITIN. Errors will delay any refund.
- Missing signatures: Your signature is required, and both spouses must sign a joint return.
- Incorrect residency details: Part-year residents must enter their full months in Idaho during 2025. Nonresidents should not answer that question. All part-year residents and nonresidents must enter their current state of residence.
- Claiming the Food Tax Credit when someone can claim you: Check line 32c and enter zero on line 63 if someone else can claim you as a dependent.
- Incorrect Idaho percentage: Line 38 cannot exceed 100% or be less than zero. Round as directed in the instructions.
- Changing donations after filing: Donations on lines 54 through 61 cannot be changed once made. On an amended return, they cannot be less than the original amounts.
- Including the original return with an amendment: Complete the entire amended form and schedules using corrected amounts, but do not include a copy of your original return.
Questions people ask
Can a part-year resident or nonresident claim the Food Tax Credit?
Part-year residents can claim a prorated credit against their tax due, but cannot receive a refund of any excess credit. Nonresidents do not qualify.
Can I use Form 43 to amend my return?
Yes. Check the amended-return box at the top and enter the number for your reason for amending. Complete the entire form and schedules with corrected amounts. Depending on the reason, include the required supporting documents or explanation.
What if I do not have a Social Security number?
Enter your ITIN. If you applied for an ITIN but have not received it before filing, enter “Form W-7” and include a copy of your federal Form W-7. Provide the ITIN to the Tax Commission when you receive it. If you do not have or are not required to have an SSN or ITIN, enter “NRA.”
Can I claim a credit for income tax paid to another state?
Nonresidents do not qualify. Part-year residents might qualify when Idaho and another state tax the same income while they are Idaho residents. Use Form 39NR, Part C, and include the other state’s return. Use a separate Form 39NR for each state if the credit applies to more than one state.