Re-aging debt occurs when there is a restart on the clock of an old debt's statute of limitations. The statute of limitations (often four years or more) and items still appearing on your credit history (usually seven years) are based on the last activity of the debt. So if you create new activity on a really old debt, you can reset the delinquency status of it. This is what we call re-aging and it could start the statute of limitations over or have it pop back up on your credit report.
This can happen a lot, especially by accident. Re-aging is usually good for the lender and not the borrower, since the lender can potentially use all of the normal legal collection options again. So what can re-age debt? Just acknowledging the validity of a debt could be considered activity. That's why it's important, especially when dealing with a collector, to not accept responsibility for a debt right off the bat.
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