Filing an amended return by regular mail can be risky, a couple learns. They asserted that they sent the return to IRS by U.S. mail in June, before the Oct. 15 expiration of the statute of limitations. But IRS didn’t receive it. The Revenue Service denied the refund, saying the couple’s claim was untimely. The taxpayer has the burden of proving that the return was mailed on time. Registered or certified mail or the use of agency-approved private delivery services are the exclusive ways by which a filer can prove that tax forms were delivered to IRS when the time of filing is in question or if the Service can’t find a return. In the case at hand, testimony from the couple’s employees that they put the return into a mailbox at the post office before the deadline wasn’t enough (Baldwin, 9th Cir.).