When and how it arrives
In the public sector: an extra annual salary (trzynastka), paid by the end of the first quarter after the year it covers. Private sector: depends on the company, from a contractual bonus to a discretionary one, typically paid between 1 and 20 December.
What to pay off first
By cost, with no sentiment: the credit card with a revolving balance. RRSO 18–20% every month. Then a lender, if you have one open. Then the cash loan. Your mortgage and even a car loan are your cheapest debts. Leave them for last.
Snowball or avalanche
Avalanche: start with the debt at the highest RRSO. That saves the most in pure maths. Snowball: start with the smallest debt; you win the feeling of closing an account, which helps you not to give up. If you know yourself and you tend to give up, pick the snowball; if you have discipline, pick the avalanche.
When the bonus isn't enough
Consider consolidation. Roll a card plus an online loan plus a small cash loan into one bigger loan at a lower RRSO and a lower payment. One condition (and it's serious): don't use the cards you just paid off. If you're not sure you can hold the line, close the cards as soon as you consolidate.
What not to do with the bonus
Spend the whole thing on presents and New Year's. January is the longest month of the year for a reason. Don't overpay the mortgage or the car loan while you still have active cards — the RRSO gap is huge and you lose. Don't pay only the minimum on every card instead of zeroing one out; the minimum is calibrated so the debt never falls.