The following rate changes went into effect on July 1, 2024:

• California changed from 7.00% to 8.00% for underpayments; the refund rate remained unchanged at 5.00%. This change was available at the time the 24.2.0.0 release was issued and was included at that time.
• Michigan changed from 9.30% to 9.50% for both underpayments and overpayments.
• The Missouri refund rate changed from 3.00% to 3.10%; the underpayment rate remained unchanged at 9.00%.
• Tennessee changed from 12.25% to 12.50% for both underpayments and overpayments.

This release also includes a rate change for underpayments effective January 1, 2025, for Colorado from 11.00% to 12.00% for both underpayments and overpayments.

The file that contains information about extensions has been reduced to include only the automatic COVID-19 extensions granted in 2020 by the jurisdictions we track. For other extensions for relief in disaster situations, please consult that jurisdiction’s website. For federal disaster relief consult https://www.irs.gov/newsroom/tax-relief-in-disaster-situations. In the cases that we do not track use the Easy Calculation tab of Instant Interest to specify the revised due date for payment of taxes.