Does making a partial payment on an old debt restart Ontario's limitation clock?

It can, under Ontario's Limitations Act, 2002. Making a payment toward a debt can be treated as a form of acknowledgment that the debt is still owed, and where that's the case, the limitation clock is generally treated as restarting from the date of the payment rather than continuing to run from whenever the debt originally became due. This means a debtor who makes even a partial payment on an old debt, perhaps thinking it shows good faith or buys time, can inadvertently give the creditor a fresh limitation period to sue on the full remaining balance.

This is a genuine trap for debtors trying to manage old debts informally, since a payment made without legal advice, intended simply to reduce what's owed or placate a creditor, can have the unintended effect of reviving a claim that might otherwise have been getting close to time-barred. Creditors, conversely, sometimes rely on a partial payment as evidence supporting a later claim that would otherwise be vulnerable to a limitation defence. Because the effect of a payment on the limitation clock can be significant either way, anyone considering making a payment on an old, disputed, or aging debt should understand this risk before doing so.