Last minute filers are rightly concerned that the IRS may not receive their documents by the due date. And in most cases, there is no way to prove when the IRS actually receives your documents. Penalties can result or elections may be invalid, if you do not file on time.

Now the IRS has issued final regulations describing how to prove that tax returns and other documents have been filed by their due date when you do not have proof of actual delivery.

The Internal Revenue Code contains a “timely mailing/timely filing rule.” Under this rule, when a return is required to be filed by a particular date and is received by IRS after that date, the postmark on the envelope in which the return is mailed is considered to be the date of filing. If a return is sent by registered or certified mail, proof that it was properly registered or certified and that the envelope was properly addressed is evidence of delivery.

There is also a “mailbox rule” under common law. When mail is properly addressed and deposited in the U.S. mail, with proper postage prepaid on it, there is a rebuttable presumption of fact that it was received by the addressee in the ordinary course of the mail.

In 1994, the IRS clarified that, other than direct proof of actual delivery, the exclusive means to establish evidence of delivery of federal tax documents to the IRS and the Tax Court is to prove the use of registered or certified mail. In the new regulations, the IRS describes the circumstances under which a private delivery service (e.g., Federal Express, UPS, etc.) can be used to satisfy proof of delivery.

The new regulations provide that, other than direct proof of actual delivery, proof of proper use of registered or certified mail (registered or certified mail sender’s receipt), and proof of proper use of a private delivery service duly designated under criteria established by the IRS, are the sole means to establish evidence of delivery of documents that have a filing deadline prescribed by the internal revenue laws.