By comparison, if you file your return even if you cannot pay the full amount due, the penalty is far less: Generally 0.5 percent per month of your unpaid taxes. After five months, assuming you had paid none of the hypothetical $1,000 due, you would have accrued 2.5 percent in interest, or $25.
And if you can put any amount toward the bill by April 17, the penalty only applies to the remaining balance.
“File and pay what you can,” Slott said. “The IRS will send a bill for the rest.”
Also be aware that requesting a six-month extension generally does nothing to delay the failure-to-pay penalties from accruing; only the failure-to-file charges are affected.
“It’s only an extension to file your return, not to pay what you owe,” Slott said. “If it were an extension to pay, everyone would do it.”