Why did I get less money in a payment than I expected?
Your payment may be less because you owed an overdue debt to a public agency. If that is the case, you should have received a “Notice of Setoff” letter. Visit GovConnectIowa and select Respond to a Letter.
The law says that the Iowa Department of Revenue may withhold money to satisfy an overdue (delinquent) debt. The official term for withholding money from a payment is "setoff".
Please note that a payment agreement does not prevent the Department of Revenue from applying payments to your outstanding balance due.