How many credit cards should I pay off at once when I'm attacking my debt?

Just one at a time, while paying the minimum on all the others. Splitting extra money across every card feels productive but is actually slower and costs more interest, because no single balance shrinks quickly. Concentrating all your extra cash on one target debt, then rolling that payment to the next once it's gone, is what creates momentum.

Which card is 'the one' depends on your method: the avalanche picks the highest APR to minimize interest, and the snowball picks the smallest balance for a faster psychological win. Either way, the discipline is the same: minimums everywhere, then everything extra on a single focus debt until it's dead. Keep making at least the minimum on the others so none go delinquent. Build the sequence at wealthserene.com/tools/debt-payoff.