There is only one change effective October 1, 2024. The Missouri refund rate changed from 3.10% to 3.20%; the underpayment rate remained unchanged at 9.00%.

Two rates were announced effective January 1, 2025, and these rates have been included in this release:

• Nebraska will change from 5.00% to 8.00% for both underpayments and overpayments.
• New Hampshire will change from 9.00% to 10.00% for underpayments and from 6.00% to 7.00% for overpayments.

Colorado had previously announced a change from 11.00% to 12.00% for both overpayments and underpayments; this change was included in the 24.3.0.0 release.

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.

Only one rate change went into effect on April 1, 2024. The Missouri refund rate changed from 2.70% to 3.00%; the underpayment rate remained unchanged at 9.00%.

This release also includes a rate change for underpayments effective July 1, 2024, for California from 7.00% to 8.00%; the refund rate will remain unchanged at 5.00%.

The following rate changes became effective January 1, 2024. As noted with release 24.1.0.0, not all jurisdictions had published their rates for the first quarter of 2024 when that release was posted on January 2, 2024. The following changes have been added:

• Pennsylvania changed from 7.00% to 8.00% for underpayments and from 5.00% to 6.00% for overpayments.
• Rhode Island changed from 6.25% to 8.50% for overpayments; the rate for underpayments remained at 12.00%.
• Texas changed from 8.50% to 9.50% for underpayments and from 3.018% to 4.981% for overpayments.

In addition, programs change were made to accommodate four decimal places for the new Maryland rate of 10.0075% for both overpayments and underpayments.

The following rate changes became effective January 1, 2024 (NOTE: As of January 2, 2024, the date of this release, Alaska, Pennsylvania, and Texas had not yet published their rates for the first quarter of 2024; these may become available in an interim release later in the month):

• Colorado changed from 8.00% to 11.00% for both underpayments and overpayments.
• Florida changed from 11.00% to 12.00% for both underpayments and overpayments.
• Georgia changed from 10.50% to 11.50% for both underpayments and overpayments.
• Iowa changed from 6.00% to 10.00% for both underpayments and overpayments.
• Idaho changed from 5.00% to 6.00% for both underpayments and overpayments.
• Illinois changed from 7.00% to 8.00% for both underpayments and overpayments.
• Indiana changed from 2.00% to 4.00% for both underpayments and overpayments.
• Kansas changed from 6.00% to 8.00% for both underpayments and overpayments.
• Kentucky changed from 8.00% to 11% for overpayments and from 4.00% to 7.00% for overpayments.
• Louisiana changed from 9.50% to 11.75% for both underpayments and overpayments.
• Maryland changed from 9.00% to 10.0075% for both underpayments and overpayments. NOTE: Maryland’s decision to extend the rate to the fourth decimal of a percentage point was not anticipated. As a result, we will have to release an interim update. For the time being the rate is in Instant Interest as 10.008%.
• Maine changed from 7.00% to 10.00% for both underpayments and overpayments.
• Michigan changed from 8.25% to 9.30% for both underpayments and overpayments.
• Minnesota changed from 5.00% to 8.00% for both underpayments and overpayments.
• Missouri changed from 6.00% to 9.00% for underpayments and from 2.40% to 2.70% for overpayments.
• Montana changed from 9.25% to 11.50% for both underpayments and overpayments.
• North Carolina changed from 7.00% to 8.00% for both underpayments and overpayments.
• New Hampshire changed from 7.00% to 9.00% for underpayments and from 4.00% to 6.00% for overpayments.
• New Jersey changed from 11.25% to 11.50% for underpayments and from 8.25% to 8.50% for overpayments.
• Ohio changed from 5.00% to 8.00% for both underpayments and overpayments.
• Oregon changed from 6.00% to 8.00% for both underpayments and overpayments.
• Utah changed from 5.00% to 7.00% for both underpayments and overpayments.
• Vermont changed from 4.00% to 8.00% for both underpayments and overpayments.
• West Virginia changed from 11.50% to 13.00% for underpayments and from 10.00% to 11.50% for overpayments.

The following rate changes are effective October 1, 2023:

• Alaska changed from 10.50% to 10.75% for both underpayments and overpayments.
• Alabama changed from 7.00% to 8.00% for both underpayments and overpayments.
• Arizona changed from 7.00% to 8.00% for both underpayments and overpayments.
• Federal changed from 7.00% to 8.00% for underpayments and from 6.00% to 7.00% for overpayments.
• Massachusetts changed from 8.00% to 9.00% for underpayments and from 6.00% to 7.00% for overpayments.
• New Mexico changed from 7.00% to 8.00% for both underpayments and overpayments.
• New York City changed from 11.00% to 12.00% for underpayments and from 6.00% to 7.00% for overpayments.
• New York State changed from 11.00% to 12.00% for underpayments and from 6.00% to 7.00% for overpayments.
• South Carolina changed from 7.00% to 8.00% for underpayments and from 4.00% to 5.00% for overpayments.
• Virginia changed from 9.00% to 10.00% for both underpayments and overpayments.

The following rate changes will become effective January 1, 2024:

• Colorado will change from 8.00% to 11.00% for both underpayments and overpayments.
• Maine will change from 7.00% to 10.00% for both underpayments and overpayments.
• New Hampshire will change from 7.00% to 9.00% for underpayments and from 4.00% to 6.00% for overpayments.

This release corrects a problem with the rates for the state of California. Here is a brief explanation:

1. On November 22, 2022, California posted rates effective January 1, 2023, of 5% for underpayments and 2% for overpayments.
2. On April 18, 2023, this change was deleted, so the most recent posted rate reverted to 3% for underpayments and 0% for overpayments. 
3. On July 28, 2023, the earlier change was reposted along with a change effective July 1, 2023, of the underpayment rate to 7% and the overpayment rate to 5%.

Because we followed the April 18 posting, the 23.3.0.0 version deleted the change effective January 1. That change has been reinstated. In addition, the July 28 change was posted after the 23.3.0.0 version was created; that change has been added to this version.

The following rate changes are effective July 1, 2023:

• Alaska changed from 10.25% to 10.50% for both underpayments and overpayments.
• Florida changed from 9.00% to 11.00% for both underpayments and overpayments.
• Michigan changed from 5.65% to 8.25% for both underpayments and overpayments.
• Missouri changed from 1.30% to 1.90% for overpayments; the rate for underpayments remained at 6.00%.
• New Jersey changed from 10.00% to 11.25% for underpayments and from 7.00% to 8.25% for overpayments.
• Tennessee change from 8.00% to 12.25% for both underpayments and overpayments.

The following changes are retroactively effective as of April 1, 2023:

• Alaska changed from 9.75% to 10.25% for both underpayments and overpayments.

The following changes are retroactively effective as of January 1, 2023:

• Earlier this year the Franchise Tax Board posted an erroneous rate change for the state of California. That change has been deleted so that the rates for underpayments and overpayments remain at 3.00% and 0.00%, respectively.
• Prior to January 1, 2023, Rhode Island charged the same rate (18.00%) for underpayments of all taxes. As of January 1, 2023, the rate for all tax underpayments other than those that are “trust fund” related dropped to 12.00%.

There are no rate changes in this release. See the release notes for version 23.2.0.0 for the 2nd quarter 2023 rate changes.

This version greatly expands the tax relief extension table. The previous version was created to accommodate tax deadline extensions for COVID-19. This version includes federal tax relief deadline extensions dating back to 2018 for various natural disasters (see the IRS page “Tax Relief in Disaster Situations“). We will continue to expand this table to include tax relief deadline extensions granted by other jurisdictions at well.

In most cases (COVID-19 being the main exception), the extension is based on what state and county the taxpayer is based in. The initial check for eligibility for the extension depends on selecting your state from the Taxpayer State pulldown. In many cases whether the extension is granted depends on what county your business is based in. However, we do not track the extensions down to that level. When we determine that you may be eligible for an extension based on your home state, we give you the official URL that outlines eligibility for the extension so that you can determine whether or not to apply it in your case.

Effective April 1, 2023, Missouri changed its refund rate from 0.8% to 1.3%; the underpayment rate remained at 6.0%.

The following rates were effective January 1, 2023:

• Alaska changed its interest rate from 8.50 % to 9.75% for both underpayments and overpayments.
• Rhode Island changed its refund rate from 3.25% to 6.25%; the interest rate for underpayments remained at 18.0%.