A timely postmark on your tax return may not be enough to avoid late-filing penalties

Because of a weekend and a Washington, D.C., holiday, the 2016 tax return filing deadline for individual taxpayers is Tuesday, April 18. The IRS considers a paper return that’s due April 18 to be timely filed if it’s postmarked by midnight. But dropping your return in a mailbox on the 18th may not be sufficient.[ … ]