A new U.S. Postal Service (USPS) processing rule (Rule 608.11) may impact how postmark dates are assigned for your mail, creating potential implications for anyone sending time‑sensitive materials. 

In December 2025, USPS began applying postmarks at regional processing centers rather than at local post offices. Since mail may take several days to reach a processing center, your mail may not receive a postmark on your intended mail date. This means that documents you drop in a blue collection box or mail from home could end up postmarked one or more days later than mailed. For items where the official postmark determines whether something is considered “on time,” that delay could matter. Where the IRS is concerned, the postmark dictates what is considered timely.

Types of Mail to Consider

Anyone sending time‑sensitive documents such as these should plan ahead to avoid postmark delays: 

• Legal documents.
• IRS forms and payments.
• Applications or filings with hard deadlines.
• Contractual notices.
• Bills or payments that require proof of mailing date.

Ensuring a Timely Postmark

Aside from filing documents such as your tax return online, the safest bet is a visit to your post office. 

Avoid:

• Self-service kiosks.
• Dropping in your own mailbox or a blue box collection site.
• Carriers like UPS or FedEx. 

At the post office: 

• Ask for a manual time stamp from the USPS employee.
• Buy postage at the counter, where you’ll receive a Postage Validation Imprint label showing the date of purchase/mailing.
• Mail via certified or registered mail for a dated receipt.

Bottom line: Mailing time-sensitive documents now requires planning ahead if you want to ensure a timely postmark date.