What two card balances cost right now
The technique
Price each card separately, per month, from the statement
People know their total card debt and almost never know what each card costs them in a month. The two numbers behave differently: the total tells you how much you owe, the per-card monthly cost tells you which one to attack. Cards quote a monthly rate, commonly around 3.5 percent, and GST at 18 percent is charged on the interest, so the statement's interest line and the GST line together are the true cost of standing still.
Take two cards: ₹1,20,000 on one and ₹60,000 on the other, both at an illustrative 3.5 percent a month. Here is what carrying each for one month costs, before a rupee of principal moves.
| Card | Balance | Interest | GST on interest | Cost per month | Cost per year |
|---|---|---|---|---|---|
| Card A | ₹1,20,000 | ₹4,200 | ₹756 | ₹4,956 | ₹59,472 |
| Card B | ₹60,000 | ₹2,100 | ₹378 | ₹2,478 | ₹29,736 |
| Both | ₹1,80,000 | ₹6,300 | ₹1,134 | ₹7,434 | ₹89,208 |
- Standing still on ₹1.8 lakh costs ₹7,434 a month, or ₹89,208 a year. None of it reduces the debt. That is the figure any consolidation has to beat, and it is a monthly figure, not an annual rate
- Card A costs twice what Card B costs, which is obvious, and Card B still costs ₹2,478 a month, which people forget. A balance that feels small enough to ignore is charging you close to ₹30,000 a year
- A card carrying a balance has no interest-free period on new purchases. Every swipe on either card joins the balance at the full rate from its transaction date, so the ₹7,434 rises with each month you keep using them






