[rbarnes01]

Last year I was hit with a failure-to-pay penalty, even though I mailed the check on the deadline. When I spoke to an IRS agent, they claimed that the payment needed to be received, not postmarked, by April 15. Never heard of that before. He was kind enough to remove the penalty because it was a first time offense.

Since then, I pay electronically. Never again.

[eigen]

from the IRS (https://www.irs.gov/filing/individuals/when-to-file)

Your return is considered filed on time if your envelope is properly addressed, postmarked and deposited in the mail by the due date.

[Tempest1981]

It's strange to me that they list them in that order... making me think they meant "addressed, stamped, and deposited", since postmarking clearly occurs later, after the others.

[bdangubic]

The IRS agent did not know the law (unlikely) or was just messing with you (likely)