Psst: You may have an extra 3 hours to file taxes

CHICAGO -- So, what if you don't drop that tax return in the mailbox at the stroke of midnight?

Officially, the IRS sticks by a passage on the agency's website: "If you do not file your return by the due date, you may have to pay a failure-to-file penalty and interest."

But experts say waiting in line at the post office on Tax Night isn't necessary.

"We certainly encourage everyone to file on time," said Tom Ochsenschlager, vice president of tax for the American Institute of Certified Public Accountants. "But if you're a little bit late, the IRS will probably be pretty reasonable."

And here's one more secret. That midnight deadline for filing taxes is actually midnight Pacific time, giving many of the nation's procrastinators as much as a three-hour reprieve.

Online filers, especially, may appreciate the time. The reality is that the annual ritual of dashing to the post office to get returns postmarked on April 15 is being replaced by late nights on the computer using tax-preparation software. A majority of returns are now filed electronically.

IRS officials acknowledged the small window of opportunity at a January teleconference, according to Kay Bell, a tax editor with Bankrate.com. That would mean 3 a.m. for East Coast procrastinators, 2 a.m. for those in the Central time zone and 1 a.m. Mountain Time.

Pushing it beyond that can be risky — even if the IRS doesn't have a room full of staffers scanning for tax returns postmarked April 16 or 17.

Either way, the last-minute filing frenzy endures. Only about two-thirds of the 141 million individual returns expected this year had been filed by the end of last week.

But is there actually a grace period?

Not officially, of course. IRS spokesman Dean Patterson declined to comment on that or discuss any policy regarding late filers. He instead referred to that passage on the agency's website, www.IRS.gov. And some experts cite court cases where filers were a day or two late and still were assessed penalties, which are figured for each day that the return is late.