You have heard the horror stories about mail sent to the IRS that remains unanswered for months. The IRS has mountains of unanswered mail pieces in storage trailers, waiting for IRS employees to process them.

Because the understaffed IRS is having so much trouble processing all the documents it receives, you need to protect yourself when you send an important tax filing due by a specific deadline.

If you can file a document electronically, do so. The IRS deems such filings as filed on the date of the electronic postmark.

If you must file a physical document with the IRS, do not use regular U.S. mail, USPS Priority Mail, or USPS Express Mail.

When you mail a document with these methods, the IRS considers it filed on the postmark date, but only if the IRS receives it. What if the U.S. Postal Service does not deliver it or the IRS misplaces it? You will have no way to prove the IRS received it—and the IRS and most courts will not accept your testimony that it was timely mailed.

Don’t take this chance. Instead, file physical documents by certified or registered U.S. mail, or use an IRS-approved private delivery service (generally, two-day or better service from FedEx, UPS, or DHL Express) to meet the IRS “timely mailing” requirement. When you do this, the IRS considers the document filed on the postmark date whether or not the IRS receives it.

Make sure to keep your receipt.