What is the collections limitation period and can CRA still collect a tax debt after 10 years?

CRA generally has a defined collections limitation period, commonly described as 10 years, after which it cannot start new legal collection proceedings on a tax debt. Once that period genuinely runs out without anything happening to extend or restart it, CRA's ability to pursue new formal collection action on that specific debt is generally over.

The word "generally" matters here, because this limitation period isn't as simple in practice as picking a start date and counting ten years forward. Certain actions can restart or extend the running of that period - making a partial payment on the debt is a common example, covered in more detail in a related question - so a debt that looks old on paper isn't automatically safe from collection just because a decade has technically passed since it first arose. Because this is a genuinely important protection with real exceptions that can extend it, don't assume an old tax debt is simply expired without confirming that nothing has happened over the years to restart the clock. If you have an old, unresolved tax debt, getting a clear picture of exactly where that limitation period actually stands is worth doing before you take any action, including making a payment, that might affect it.