41-145: Alternate Tax Calculation Worksheet 41-145 (2025)
Iowa · Iowa DOR · Used for tax years 2025
The 2025 Iowa Alternate Tax Worksheet (41-145) calculates an alternate income tax amount and compares it with the tax rate calculation to determine the smaller amount for IA 1040. It also includes steps to prorate the alternate tax between spouses who are married filing separatel
Who files this form
The 2025 worksheet may help you calculate a lower Iowa tax. It does not say that you must complete it.
All filing statuses except status 1, Single, may qualify for the alternate tax calculation. Single taxpayers may qualify for the Iowa income tax reduction instead. See the Iowa Income Tax Reduction Worksheet (41-146).
For status 3, Married Filing Separately, you must use both spouses’ combined Iowa taxable incomes. Additional restrictions apply if either spouse has a net operating loss (NOL) that will be carried forward.
What you'll need
Have the following information available to complete the worksheet:
- Iowa taxable income from IA 1040, line 4.
- The itemized or standard deduction from federal Form 1040, line 12e.
- Any personal exemption deduction allowed for federal purposes.
- The QBI deduction from federal Form 1040, line 13a.
- Any NOL carryover from IA 1040, Schedule 1, line 17, column B.
- Any taxable lump-sum distributions reported on federal Form 4972, line 8.
- Whether you or your spouse was age 65 or older on December 31, 2025.
Married filing separately taxpayers need both spouses’ income information. If a spouse with an NOL elects not to carry it forward so the alternate calculation can be used, include a statement with the return saying that the spouse will not carry the NOL forward.
How to file
Complete the worksheet and compare the tax amounts on lines 4 and 5. Enter the smaller amount on line 6.
- Filing statuses 2, 4, or 5: Also enter the line 6 amount on IA 1040, line 5.
- Filing status 3: If line 4 is less than line 5, complete lines 7–11 to divide the alternate tax between spouses. Transfer line 10 to your IA 1040, line 5, and line 11 to your spouse’s IA 1040, line 5. If line 5 is less than line 4, enter each spouse’s tax from the tax rate calculation on their IA 1040, line 5.
If you use the alternate tax calculation instead of the tax rate calculation, check the box in IA 1040, Step 5.
The worksheet does not provide mailing, e-filing, or delivery instructions.
Common mistakes
- Missing the alternate-tax checkbox: Check the box in IA 1040, Step 5, if you use this calculation instead of the tax rate calculation.
- Leaving out a spouse’s income: Status 3 filers must use both spouses’ combined Iowa taxable incomes. The alternate calculation will not be allowed if the other spouse’s income is missing from IA 1040, Step 2.
- Not dividing the tax between spouses: Status 3 filers must prorate the alternate tax using lines 7–11.
- Overlooking the NOL restriction: Married filing separately taxpayers cannot use the alternate calculation if one spouse has an NOL that will be carried forward. If that spouse elects not to carry it forward, include the required statement with the return.
Questions people ask
Can single taxpayers use this worksheet?
No. Filing status 1, Single, is excluded. Single taxpayers may qualify for the Iowa income tax reduction described in Worksheet 41-146.
What amount goes on line 2 for 2025?
Enter $13,500, or $32,000 if you or your spouse was age 65 or older on December 31, 2025.
How does the worksheet compare the two tax calculations?
Line 4 multiplies the income on line 3 by 4.3%. Line 5 multiplies Iowa taxable income from IA 1040, line 4, by 3.8%. Status 3 filers calculate line 5 separately and combine the amounts. Line 6 uses the smaller amount.
How is alternate tax divided when spouses file separately?
Use lines 7–11. Line 9 divides line 7a by line 8 and rounds the result to the nearest tenth of a percent. Line 10 applies that percentage to line 6 for your share. Line 11 assigns the remaining amount to your spouse.