Whether you’re expecting a refund or you have to supplement what you’ve already paid, there’s ample reason to be on time sending in your tax forms this year.

Penalties for being late can be quite high for those who owe Uncle Sam, and those who expect to receive refunds could lose them because of late filing.

And this year people in Suffolk will have just a little less time to file if they plan to do so via a personal exchange at their local post office.

New this year, the Suffolk post office will close its doors at 5 p.m. on Tax Day, instead of 6 p.m.

“We’re adjusting to the flow of customers that come through on tax day,” Postmaster James Colston said. “The amount of people coming through during that extra hour we’ve been staying open the past few years doesn’t justify it.”

Colston explained that in past years only two or three customers dropped off forms between 5 p.m. and 6 p.m.

“More and more people are filing taxes online,” Colston said. “The tax forms we have in the lobby have just sat there over the past few weeks. No one has really taken them. Based on what the IRS sends us each year, the volume of forms is getting to be fewer and fewer.”

If you don’t make it to the post office before 5 p.m., however, don’t fret.

“We have an automatic postal center in the lobby that [customers] can weigh the envelopes and buy stamps through,” Colston said.

The envelopes must then be dropped off at a mailbox before the last designated pick-up time or taken to the Norfolk office, which is open to the public on Tax Day until 10 p.m.

“The sticker the automated machine prints off has a date on it, but that date is only representative of the date of purchase,” said Fran Sansone, spokeswoman for the U.S. Postal Service. “The IRS won’t accept that date as the date of deposit. If you use the automated machine, you have to get it to a drop-box before the last pick up time or to Norfolk.”

Cutting corners and skipping the post office, however, isn’t recommended.

“If you mail a letter and are short postage, the IRS will send it back and consider it late,” Colston said.

“That’s a biggie to watch out for,” said Carrie Bott, H&R office coordinator and tax professional. “If you’re late on filing, it can be up to 25 percent of what you owe. When that deadline hits, people start looking for shortcuts, and the results can hurt.”

Bott said that people in a hurry to finish and file their taxes also are more prone to make mistakes with simple addition and subtraction.

“Slow down, use a calculator and double- and triple-check your work,” Bott said. “If you file online, you don’t have to worry about all that, but if you’re filling it out yourself, you have to be careful.”