Here’s the thing: even a small, partial payment on an old debt can revive the statute of limitations. That can allow the creditor to sue you and get a wage garnishment order so it can take money right out of your paycheck.

If it were the original creditor suing you, you might resign yourself to the situation. But often the company filing the lawsuit is not the original creditor. Many times, the company that originally loaned you the money has long since written off the account, gotten a tax break for bad debt and sold the account to a collection agency. So the entity suing you may be  a collection agency which purchased your debt for 2 or 3 cents on the dollar–or even less.

The Wall Street Journal has done some good stories lately on the debt-buying industry, and has one today about the FTC’s settlement with Asset Acceptance, one of the largest debt buyers. The FTC alleges people were coerced into paying debts beyond the statutes of limitations. In some cases, the FTC contended, Asset Acceptance reported details of the out-of-statute debts to the credit bureaus in violation of federal credit reporting laws.

Most of us feel a moral obligation to pay what we owe. If bad decisions or bad circumstances have left you with unpaid bills, though, you could be stepping on a land mine if you make a partial payment on old debts. Before you pay, you should understand whether the debts are within the statute of limitations. If they’re not, and you still want to pay, consider negotiating a lump-sum settlement that includes the collector’s promise not to resell any portion of the debt. This is tricky business, though, and you should educate yourself thoroughly before you make the attempt. DebtCollectionAnswers.com, a site run by credit expert Gerri Detweiler, is a good place to start.

But a Facebook fan pointed out that not all debt collection calls are based on a legitimate debt:

After my father died, my mother was contacted by someone falsely claiming he owed a medical bill, offering to process the payment over the phone. She knew it was false [because] she handled the bills, so she told them not to call again.

Survivors also should beware of calls from purported charities, claiming that the deceased promised them a donation of some kind.

When it comes to claims against an estate, you’ll want to see proof that the deceased owed the debt or made any kind of financial promise. Don’t take a caller’s word for it.

Answer: The clock on reporting most negative marks begins when the account first goes delinquent and isn’t reset when a creditor or collection agency updates or sells the debt. If the collection agency continues to report the debt after seven years and 180 days passes, you should be able to dispute the entry with the credit bureaus and get it removed from your credit reports.

You also may need to be concerned about your state’s statute of limitations for this debt. This statute affects how long you can be sued over a debt, which can vary from three to 15 years. In some states, the statute can be extended if you make a payment on the debt or even acknowledge it as your own.

If you’re at risk of being sued, you may want an attorney’s advice about how to proceed and whether you should try to settle this account. You can get a referral from the National Assn. of Consumer Advocates at http://www.naca.net. Even if you aren’t at risk of a lawsuit, it could pay to get this debt resolved. As you’ve learned, mortgage lenders typically aren’t willing to lend money to people with open collection accounts on their reports.