Do I need a written contract to sue someone for money they owe me in Ontario?

No, a written contract is not strictly required to sue for a debt in Ontario. Oral contracts are legally enforceable, and courts regularly hear cases based on spoken agreements or informal understandings. However, without a written record, your case depends heavily on credible witness testimony, contemporaneous documents, and any circumstantial evidence that supports your version of the agreement.

Evidence that can help establish an oral agreement includes: text messages or emails referring to the loan or services, bank transfer records showing money sent, acknowledgment by the other party that they received the funds, and any partial payments made. Courts assess credibility and the balance of probabilities — in civil cases, you only need to show it is more likely than not that the agreement existed and the debt was not repaid.

The limitation period applies regardless of whether the agreement is written or oral — generally two years from when you knew the debt was owed and not being paid. Waiting too long can eliminate your right to sue even if your evidence is strong.

If you are owed money under an informal arrangement, document everything you have now: notes of conversations, all electronic communications, payment records. A lawyer can assess whether your evidence is sufficient to support a claim and advise on the most appropriate forum (Small Claims Court versus Superior Court, depending on the amount).