For those who haven’t filed taxes yet this year, Thursday is the final day to either do so or file an extension without having to pay a late-filing penalty.

“At this late date it’s probably best to file an extension,” said IRS spokesman Dan Boone.

Last-minute filers can request an extension by submitting form 4868, which is available free to everyone on www.irs.gov. The extension will grant an additional six months, until Oct. 15, to file the tax return.

“The biggest error of all is to miss the deadline if you owe on your taxes,” Boone said. “Failing to file either a return or an extension will add the late filing penalty to what you already owe.”

That penalty is based on the amount due and how long the debtor takes to file. The IRS will charge five percent of what is owed for each month the taxpayer is late, up to 25 percent. Those charges will go along with normal monthly interest fees, currently at five percent, as well as late payment penalties, which are typically one percent. Boone said the IRS is open to working with taxpayers during rough economic times.

“We know some people have had a rough year financially,” he said. “ If they owe, we encourage them to file on time, pay what they can and set up an IRS installment agreement.”

Boone said that reasonable payment plans would be accepted.

“We really are pretty flexible. If you owe $25,000 or less, you can go to irs.gov and do an online payment agreement and propose a payment plan.”

Boone also said that many taxpayers are eligible to file electronically for free using software on the IRS website.

“If your income is $52,000 or less, you can use Free File to go ahead and file your tax return,” he said.

People who wish to take advantage of this filing method should go online to www.irs.gov and click the Free File link.