Iowa School District Surtax Calculator

Iowa school district surtax

How the surtax works

The Iowa school district surtax is not a rate on your income: it is a percentage of your Iowa income tax, set by the district you live in. The IA 1040 instructions put it in one line: "Multiply the amount on line 18 by the surtax rate and enter the result" on line 19. Line 18 is your Iowa tax after the exemption credits and your other nonrefundable Iowa credits. A 5% surtax on a $2,240 line 18 balance is $112, about 0.19% of the $60,000 of taxable income in the default example.

The district that counts is the one you lived in on the last day of the tax year, December 31, 2025 for calendar-year filers, not the district where your children go to school. People without children in public school owe it as well. Your district may not share the name of your town; the Department suggests your voter registration card or the "school surtax" option at tax-mapper.iowa.gov. Part-year residents and nonresidents follow Step 1 of the IA 1040 instructions.

Your county and district numbers on the IA 1040

Step 1 of the IA 1040 asks for two codes from the same table: the two-digit number of the county you lived in on December 31 and the four-digit number of your school district, such as 77 for Polk County and 6101 for Southeast Polk. You enter the district number even if you have no children. Besides your voter registration card and the Tax Mapper, the Department points to your county assessor's website. Nonresidents who did not live in Iowa at all during the year enter 0000 and owe no surtax; part-year residents who moved out before December 31 enter 9999 and also owe none; part-year residents who moved in use the district they lived in on the last day of the year and may owe it. Servicemembers use the district of their Iowa residence even when stationed elsewhere.

Estimating line 18

For 2025 Iowa has a flat 3.8% tax on Iowa taxable income (line 4). The exemption credits come off that tax: $40 for the personal credit, which counts twice for married filing jointly and head of household; $20 for each person 65 or older or blind; and $40 for each dependent. A married couple with two children and $90,000 of taxable income owes $3,420.00 at 3.8%, subtracts $160.00 of credits and has $3,260.00 on line 18. In Southeast Polk the 5% surtax is $163.00.

Two things the estimate leaves out. Filers other than single can use the alternate tax computation (4.3% of income above $13,500, or $32,000 if you or your spouse was 65 or older), and single filers may qualify for an income tax reduction; either can lower line 5. Credits such as the tuition and textbook credit or the out-of-state tax credit also cut line 18; enter them as other credits, or switch the calculator to your actual line 18.

Retirees and the surtax

Because the surtax is a share of your Iowa tax, anything that lowers the tax lowers the surtax too. Since tax year 2023 Iowa excludes retirement income from taxable income for people who are 55 or older on December 31, disabled, or a qualifying surviving spouse, and the exclusion covers pensions, IPERS, IRAs, 401(k) and 457(b) plans. A retired couple whose income is all from those sources can have no Iowa tax on line 18 and so no school district surtax, whatever their district's rate. For a married couple where only one spouse qualifies, the other spouse's retirement income stays taxable.

Rates in the largest districts

Rates in the 2025 table run from 0% to 20%. Of the 324 districts listed outside the EMS counties, 39 have no surtax and 41 charge 5%, the most common rate. Many large districts, including Des Moines, Davenport, Waterloo and Council Bluffs, charge nothing. At the top of the table, Postville, Fremont-Mills and East Mills charge 20%: on the same $2,240 line 18 balance as the default example, that is $448 instead of $112. The rate a district shows is the same in every county it reaches, except in the six EMS counties below.

From Iowa Department of Revenue form 41-027, "Iowa Counties, School District Numbers, Surtax Rates for 2025". A district that reaches several counties is listed under each one.

The EMS surtax in six counties

Counties may also add an emergency medical services (EMS) income surtax. For 2025 only Appanoose, Cass, Pocahontas, Sac, Shelby and Winnebago counties have one, and the table already includes it: rates for residents of those counties include a 1 percent local option surtax. That is why Albia shows 2% under Appanoose County and 1% under Monroe County. Pick the county you actually live in and the calculator applies the right figure.

The surtax is added to your Iowa tax on line 20 of the IA 1040, total state and local tax, so it raises what you owe or trims your refund. Compare your take-home pay with the Iowa salary calculator and Iowa salary after taxes. If you cross a state line for work, see work in Illinois, live in Iowa, work in Nebraska, live in Iowa and work in Minnesota, live in Iowa, and for other local taxes local income tax by state.