I've counseled a number of people lately who, suspecting that they had to pay taxes, didn't file their returns — for years.

The Internal Revenue Service has finally caught up with them, and now they are facing possible tax liens. They never contacted the IRS or any professional to discuss their options. They just didn't file.

"Why?" I asked.

"Because I was afraid," was the usual answer.

If you've done your tax return and realize you owe but can't pay, the worst thing to do is nothing. Eventually the IRS will track you down, and by then the penalties and late fees will make your debt that much larger.

In fact, the interest on unpaid tax debts is compounded daily and is charged from the due date of the return until the date of payment. The IRS charges the Federal Reserve's benchmark short-term interest rate plus 3 percent, which these days means 8.25 percent.

Although the IRS doesn't have the stormtrooper reputation it once did, it hasn't gone SpongeBob-SquarePants soft. The agency won't giggle and forgive your transgression like the sweet sea creature in the Nickelodeon cartoon. It will come after you hard.

If nothing else, at least file your tax return — even if you can't pay the full or even a partial amount. The total penalty for failure to file and to pay can be 47.5 percent (22.5 percent for late filing, 25 percent for late payment) of the tax owed. Filing at least saves you the 22.5 percent portion of the penalty.

This time of year, companies prey on individuals who either have not filed and owe, or have filed and can't pay. These firms promises that they can get the IRS to settle your tax debt for a fraction of what you owe.

In the majority of the cases, this is just a deception. Essentially, what these promoters do is have you apply for what's called an offer in compromise, or OIC. This allows the IRS, under certain circumstances, to accept less than the full tax payment.

An OIC is tough to get. Last year, the IRS received 59,000 requests, but only 15,000 were granted.

You have to be experiencing some unusual economic hardship to qualify. The IRS will not accept an OIC unless the amount you offer to pay in lieu of your full tax obligation is equal to or greater than what the agency thinks it can reasonably collect from you.

That means you are expected to exhaust all ways to pay your tax bill, including liquidating any assets and bank accounts. You'll have to show that you don't have any real estate, automobiles or other assets that can be sold. In addition, the IRS will look at your present and future income, less certain amounts allowed for basic living expenses.

Instead of contacting one of those promoters promising to get your tax bill cut to pennies on the dollar, go through the checklist on IRS Form 656, Offer in Compromise, to determine if you are eligible. This form has all the instructions for submitting an offer. There's also a worksheet — you can fill it in online at www.irs.gov — that is not too complicated and can help you determine how much you would be expected to offer. Look for the OIC "fill-in format."

Last year there were some major changes to the OIC program. In order to be granted an OIC in many cases, you have to make a 20 percent, nonrefundable, upfront payment along with your OIC offer. If you've completed your return and you find you can't pay your tax debt, call (800) 829-1040. If you are a small-business owner, call (800) 829-4933.

If you cannot pay the full amount due on your return, ask to make monthly installment payments. You'll have to pay a one-time fee of $105. To request an installment agreement, use IRS Form 9465, Installment Agreement Request, with your return.

Michelle Singletary (singletarym@washpost.com) writes for The Washington Post.