Iowa 2025 W4. 13 released new income tax withholding formulas and tables for 2025 to account for inflation and changes to individual. 1, 2025, iowa's income tax will drop to a 3.8% flat rate for all taxpayers — down from a top income tax rate of 5.7% in 2024.

1, 2025, iowa’s income tax will drop to a 3.8% flat rate for all taxpayers — down from a top income tax rate of 5.7% in 2024. Below we’ve outlined the basics of what you need to know and what you should do to help your employees have the right state tax withholding.