Indiana DOR: USPS Postmark Changes Impact Tax Timeliness

Detected March 17th, 2026

Summary

The Indiana Department of Revenue (DOR) has issued a notice regarding changes to USPS postmark rules. These changes could impact the timeliness of tax filings and payments, potentially leading to late fees. The DOR recommends using its online portal, INTIME, or requesting a manual postmark for mailed items.

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What changed

The Indiana Department of Revenue (DOR) is alerting taxpayers to changes in USPS postmark processing that could affect the determination of tax filing and payment timeliness. Previously, the postmark date was used to establish when a document was mailed. However, USPS now applies a postmark reflecting the date of first automated processing, which may be days after the item was mailed. This discrepancy could result in taxpayers facing late fees, penalties, or interest if their mailed submissions are postmarked later than the date they were actually sent.

To mitigate these risks, taxpayers are strongly advised to utilize the DOR's online portal, INTIME, for all payments and responses to correspondence, as electronic submissions are instant and provide immediate confirmation. For those who must mail documents, the DOR recommends requesting a manual postmark at a USPS retail counter, mailing at least one week before the deadline, or using Certified Mail for proof of mailing. Failure to account for these postal delays could lead to financial penalties and interest charges.

What to do next

Review USPS postmark policy changes and their impact on tax filing deadlines.
Prioritize electronic submissions via INTIME for payments and responses.
If mailing is necessary, request a manual postmark and mail at least one week prior to the deadline.

Penalties

Late fees, penalties, or interest may be assessed due to delayed postmarks.

Source document (simplified)

USPS Postmark Change

The USPS updated its postmark rules. A postmark will not be applied the day you mail something or drop it off at the post office. It will reflect the date of the first automated processing operation, which could be days later. Because the Indiana Department of Revenue (DOR) uses the postmark to determine timeliness, a mailing delay could lead to late fees, penalties, or interest.

The best way to pay and respond: INTIME

To avoid postal delays entirely, use Indiana’s secure online portal, INTIME. Electronic submissions are instant and provide immediate confirmation of receipt.

1. Make a payment

Bank Account (Free): Pay via Automated Clearing House (ACH) with no transaction fees.
Credit/Debit Card: Submit payments for a small processing fee.
Locate the “Payments” panel on INTIME’s homepage and select “Make a payment.” You will need your Social Security Number (SSN) or Letter ID.

2. Respond to Letters or Notices

Upload documents: Directly submit requested documents through INTIME.
Locate the “Respond to correspondence” panel on the main page. You will need the Letter ID from the correspondence you received.

If you must use the mail

If you choose to mail your return or payment, take these steps to ensure it is considered timely:

Request a manual postmark: Present your mail piece at a USPS retail counter and specifically request a “manual (local) postmark.” This aligns the postmark with the date the USPS took possession.
Mail early: USPS recommends mailing items at least one week before the deadline to account for possible processing delays.
Use Certified Mail: For proof of mailing, customers can purchase Certified or Registered Mail services to obtain a dated receipt.

Additional Resources

Payment Plans: Find information on monthly installments or money order instructions on the DOR payments & billing page.
USPS rule details: Read the full rule on the Federal Register's official webpage.