Balance Transfers: Running the Actual Numbers

What a Balance Transfer Is

You move a balance from one card to another, usually to take advantage of a promotional rate on the receiving card. The debt does not go away and the amount does not change. What changes is what you are charged to carry it, and for how long.

Transfers are genuinely useful. They are also marketed heavily, because a promotional period that expires with a balance still on it is profitable for the issuer. Both things are true at once, which is why the arithmetic matters more than the offer.

The Four Numbers You Need

Everything about whether a transfer is worth doing comes out of four figures:

• The transfer fee: charged up front as a percentage of the amount moved, and added to the transferred balance.
• The length of the promotional period: in months, starting when the transfer posts, not when you applied.
• The rate after the promotional period ends.
• What you can realistically pay each month.

The Trap: New Purchases

The most common way a transfer goes wrong has nothing to do with the transfer. It is that people start using the card.

On many cards the promotional rate applies to the transferred balance only. New purchases are charged at the standard rate, and because you are carrying a balance, they have no grace period, so they accrue interest from the day of purchase. Meanwhile federal payment allocation rules mean anything you pay above the minimum goes to the highest-rate balance first, which is the purchases. Your transferred balance sits there barely moving while you believe you are paying it down.

The clean approach is to treat a transfer card as a payoff vehicle and nothing else. Do not carry it. Do not put it in a digital wallet. It has one job.

What Happens at the End of the Promotional Period

The promotional rate ends on a date, not when the balance is cleared. Any remaining balance moves to the standard rate from that point.

Worth confirming before you apply: whether the card charges deferred interest. Under a deferred interest structure, if the balance is not fully cleared by the end of the promotional period, interest is charged retroactively on the entire original amount from the transfer date, not just on what is left. This is more common on store cards and retail financing than on general-purpose transfer offers, but it is the single most expensive term to miss.

Effects on Your Credit

A transfer usually involves applying for a new card, which means a hard inquiry and a new account, both of which can lower a score modestly in the short term. Working the other way, opening a new line increases your total available credit, which lowers overall utilization and tends to help.

The larger factor is the card you transferred from. Closing it removes its credit limit from your utilization calculation and, if it is an old account, shortens your average account age. Keeping it open with a zero balance is usually better for a score. Keeping it open and using it again is what undoes the whole exercise.

When a Transfer Is Not the Right Tool

• When the balance cannot realistically clear within the promotional period. A consolidation loan with a fixed term and a fixed payment may cost less over the full period than a promotional rate that expires partway through.
• When your credit will not qualify you for a good offer. The advertised terms go to the strongest applicants; a weaker offer may not beat what you have.
• When the balance keeps growing. A transfer addresses the cost of debt, not the cause of it. If spending exceeds income, moving the balance buys time and nothing else.
• When the fee outweighs the saving. On a small balance you will clear in a few months anyway, the up-front fee can exceed the interest avoided.

Before You Apply

• Write down the four numbers. Do the division.
• Confirm whether interest is deferred.
• Check whether the promotional rate covers new purchases or the transfer only.
• Confirm the transfer fee and whether it is capped.
• Keep paying the old card until the transfer posts, it can take a couple of weeks, and a missed payment in the gap undoes the benefit.
• Decide in advance what happens to the old card.