Most new cards offer an introductory APR (annual percentage rate) for 12 months or more from the date the card is opened, and in some cases the introductory APR exists for purchases as well. Promotional APRs on existing credit cards are sometimes offered throughout the year and can range between 13 and 20 months. When evaluating balance transfer offers for new or existing cards, always look for those that offer the longest duration, since this will give you more time to save on interest and help you pay down the balance faster.

In general, balance transfers have one interest rate, and other transactions—like purchases and cash advances—have their own interest rates. This is important to know, because when you pay more than the minimum amount, issuers are required to apply that extra amount you paid to the debt with the highest interest rate (whether that be your balance transfer, purchases or access checks). Always check the interest charge calculation section of your statements.

This is the standard rate on your account that will be applied to any unpaid portion of the balance transfer amount after your promotional rate expires. It’s important to be prepared and aware that your minimum payment and interest charges may increase based on the higher go-to rate.

Balance transfer fees are often 2–5 percent of the transferred amount up front, or a minimum of $10 (this fee is added to your total balance transfer). On a $5,000 balance transfer, that could mean a fee between $100 and $250. Include the fee in your calculations to figure out if you’ll save money over the long run. Remember, the savings from the lower interest rate will often be greater than the transfer fee.

Processing a balance transfer can take two weeks or more if requested as part of a new credit card application. Processing time on an existing credit card may take up to five days. Don’t fall behind on your payments to the old card. And, once the debt is moved to the lower rate card, be careful not to incur more debt on the old card.

The higher your credit score, the better your chances of receiving low promotional rate balance transfer offers. Improving your credit score starts with an understanding of what makes up your score and the agencies that create your credit report.