where would this be entered on the 2020 tax form?

In March 2022, the Ferguson were audited by the Iowa Department of Revenue for tax years 2019 and 2020. The audit proposed no changes for the 2019 tax return. However, the Fergusons were assessed $2,250 additional income tax for 2020 (no interest or penalties were assessed). The Fergusons agreed with the assessment and paid the $2,250 immediately.