If you’re not going to be ready to send Uncle Sam your 1040 on April 15, you won’t be alone.  The late filing of federal taxes is anything but uncommon and the U.S. tax code is structured to recognize the inevitability that some of us aren’t going to meet the usual deadline.  However, the laws are not arranged in a way designed to give you any extra time with respect to actually paying your taxes.

You can get by with late filing of federal taxes, but you can’t escape your obligation to pay on time.

Here’s how late filing works:  If your returns aren’t going to be ready, you can complete and submit Form 4868 by April 15.  This “Application for Automatic Extension of Time to File U.S. Income Tax Returns” (what a pithy title, huh?) will automatically extend your deadline until the second week of October.

Completing a 4868 will not, however, completely alleviate your obligation to pay income taxes until October.  The IRS still wants your money in April.  Thus, you’re expected to submit payment with the application for a time extension–even though you probably don’t really know how much you owe at that point.  If you overpay, you’ll get the remainder back in the form of a refund.  If you underpay, you’ll still be on the hook for the balance due.

It’s actually a little worse than that with respect to underpayment.  If you underpay when you submit your application for an extension, you’ll be responsible for the remaining tax liability PLUS fees and interest charges.

Basically, asking for extra time to file is going to keep you within the law, but it isn’t going to give you a way to delay actual payment.  If Federal law requires that you file income tax returns, you have two choices to stay within the law.  You can either complete your returns on or before April 15 or you can request additional time via a 4868 submission and then complete your filing in October.  Either way, however, Washington wants your money on time.

Although you’ll still owe interest and penalties on unpaid taxes with a 4868, you can avoid additional expenses.  Jen Jones explains how the IRS penalizes those who don’t “get permission” to wait until October:

A late filing penalty results in a penalty rate of 5% for each month or partial month that the payment is late, with a maximum penalty of 25%. If you previously filed a Form 4868 before April 15^th, you will not receive this penalty unless you miss the new due date of October 15^th. The late filing penalty reaches the maximum penalty after five months, but continues at a penalty of 0.5% for each month up to 45 additional months. If you wait the entire period of time, this can result in a total of 47.5% penalty. This penalty is based on the amount required to be shown on the return, not the amount shown as due. Also, if you are audited and the actual tax liability is higher than the original balance, you will have to pay the late filing penalty on the difference.

The best advice?  File on time and pay up as soon as you can.  If you want a vivid example of just how ugly things can get if you don’t file your taxes on time, take a look at Charles O’Byrne.  The New York Governor’s former Chief of Staff amassed a shocking debt to the government after failing to settle up his tax bills.  Although O’Byrne’s lawyers are hoping to convince the courts to cut him some slack with some creative argumentation, the rest of us probably can’t count on a finding of “late filing syndrome” to save us!

NOTE:  If your late filing of federal tax situation involves past years remember that, as the IRS says, “it’s never too late to file.”  You can find the government’s recommendations on handling older tax obligations here.