Americans only have a few hours to send in their tax returns or file for an extension.

Tax experts say most people who haven't done their taxes yet should file an extension, but that doesn't mean they are off the hook.

"If you owe money, you need to make sure you pay at least 90% of what you owe," says Sal Albanese. "Otherwise that extension becomes invalid."

Tax experts say filing this year can be tricky because of the new advanced child tax credit and the third round of stimulus payments.

The penalty for not filing taxes is 10 times higher than the penalty for not paying.

Employees at H&R Block in Hicksville tell News 12 they will be in the office until midnight helping last minute tax filers get their taxes done electronically by the deadline.

"It gets a little hectic, a little stressful," says Tom Lucurto. "We try to do our best to calm everybody down."

The IRS is warning about a possible delay because staffing levels are at their lowest level since 1970. The agency says there is a plan in place to hire 10,000 more workers.