What are acceptable proofs of filing a tax return?

There are five ways to file that the IRS recognizes as providing proof of time of filing. 1. USPS Registered mail – You must keep your receipt to prove time of mailing.  2. USPS Certified mail – You must keep the green card proving time of delivery.  3. IRS approved e-filing – You must retain your electronic receipt as proof of filing.  4. IRS approved Private Delivery Services such as DHL Express Same-Day, Fed Ex Overnight, UPS Next Day or Second Day services.  Other services from these Private carriers are not acceptable.  5. USPS Regular First Class mail.  You must make a copy of your envelope showing postmark, but this is the least reliable method.