Why a carried-over card balance costs so much more than any other EMI
Credit cards charge interest on a monthly basis, not an annual one. A rate of 3.5 per cent a month works out to 51.1 per cent annualised, before GST. That number has no direct comparison in the home, car, personal or education loan markets.
Three rules, from the RBI Master Direction on Credit Card and Debit Card Issuance and Conduct, 2022 as amended on 7 March 2024, shape the arithmetic. The minimum amount due must be computed so there is no negative amortisation on the principal. Unpaid taxes, levies and charges are expressly prohibited from being capitalised for charging or compounding of interest. The interest-free period is available only if the total amount due is paid in full by the due date; a part payment loses it for that cycle.
Worked example: 1 lakh at 3.5 per cent a month
Enter a balance of ₹1,00,000, a finance charge of 3.5 per cent a month (a sample inside the current published range of about 1.99 to 3.75 per cent a month, about 24 to 45 per cent a year, with premium cards at the low end and standard cards at the top), and set the page to a fixed payment of ₹10,000 a cycle. The arithmetic for cycle one runs:
| Item | Amount |
|---|---|
| Finance charge: 1,00,000 x 3.5 per cent | ₹3,500 |
| GST on finance charge at 18 per cent | ₹630 |
| Total amount due | ₹1,04,130 |
| Payment made this cycle | ₹10,000 |
| Of which GST (paid first) | ₹630 |
| Of which interest | ₹3,500 |
| Of which principal | ₹5,870 |
| Balance into cycle two | ₹94,130 |
Carry that rule across the whole run and the balance clears in 14 months. The total interest is about ₹26,835 and the total GST on interest is about ₹4,830. On top of the ₹1,00,000 principal the balance cost close to ₹31,665 in charges.
Minimum due: the longest route to zero
Set the same ₹1,00,000 at the same 3.5 per cent, but pay the minimum amount due alone (5 per cent of the statement, with a ₹500 floor). The simulation now runs 256 months, which is over 21 years. Total interest comes to roughly ₹3,02,251 and GST to another ₹54,405. This is the arithmetic of a slow payoff on a high monthly rate.
The minimum due is not a free period: it is the regulator-imposed floor on how slowly a balance may be unwound without going negative on principal. A real card will nudge that figure upwards if the payment is too small, which this simulation makes visible by stopping where principal stops reducing.
EMI conversion: the issuer's cheaper rate
Most issuers offer a conversion facility that turns a statement balance into an equated monthly instalment at a rate well below the revolving finance rate. Convert ₹1,00,000 into a 12-month EMI at a sample 18 per cent per annum with a one-time fee of ₹300, and the EMI works out to about ₹9,168 a month. Interest across the year comes to about ₹10,016. GST at 18 per cent applies to both interest and fee, which is close to ₹1,857 in all.
Total paid: about ₹1,12,173. That is roughly ₹19,500 less than carrying the same balance at the fixed ₹10,000 payment, and far less than the minimum-due route.
The interest-free period rule, in plain English
Spending a card in a billing cycle gets a grace window between the transaction date and the payment due date. Pay the total amount due by that date, and no finance charge applies. Pay even a small amount short of the total, and the interest-free period is gone for that cycle: interest runs from the transaction date on the entire unpaid balance, per the 2024 amendment to the Master Direction. This is the single most common surprise on a card statement.
A real card also levies a late payment fee on the unpaid amount after the due date, not on the total bill, and that fee itself does not compound. The page leaves late fees out; add them separately.
What the calculator leaves out (deliberately)
- Any new spending in the cycles that follow the current statement; the page runs an open-ended simulation on one balance.
- Variation in the posting date of each transaction inside a cycle. The page treats interest on the running balance at the finance charge, which keeps the arithmetic reproducible.
- Cash advances, where interest runs from day one with no grace period and often at a different rate.
- Reward points or statement credits, which some issuers offer at a tiny fraction of the interest cost.
- Late payment fees. These are flat charges that do not compound; add them separately to the final number.
Rules from the RBI Master Direction that bind every issuer
The governing text is the RBI Master Direction on Credit Card and Debit Card Issuance and Conduct, 2022, dated 21 April 2022 and effective 1 October 2022, with amendments from 7 March 2024. The instruction set the Direction creates is binding on every card-issuing bank and non-bank in India.
Three clauses matter inside a calculator like this. The minimum amount due must reduce principal every cycle (no negative amortisation). Unpaid charges, levies and taxes cannot be capitalised for the next cycle's interest calculation. The interest-free period is lost in full, not in part, when the total amount due is not met. Everything else, including specific rates, penalty structures and conversion fees, varies by issuer and must be read from the Most Important Terms and Conditions sent by the card company.
Frequently asked questions
What is the finance charge on a credit card?
It is the interest the issuer charges each cycle on a balance that was not paid in full by the due date. The RBI Master Direction does not set the rate; banks' current schedules publish rates of about 1.99 to 3.75 per cent a month (about 24 to 45 per cent a year), with premium cards at the low end and standard cards at the top. The page's default is a sample within that range.
Does paying the minimum due keep the card safe from penalties?
It keeps the account current in the sense that no late payment fee is levied, but the interest-free period is gone and finance charges accrue from the transaction date on the entire unpaid balance. For a ₹1,00,000 balance at 3.5 per cent a month, the minimum-due route takes years to clear.
What does GST do to the cost on a card?
GST at 18 per cent applies to finance charges, to late fees, to annual fees and to the forex markup. It is calculated on the interest amount of the cycle. The RBI Master Direction expressly says unpaid taxes, levies or charges cannot be capitalised; the page respects that rule.
How does an EMI conversion work?
The issuer moves the balance into a standard equated monthly instalment schedule at a conversion rate that is well below the monthly finance charge. A one-time fee may apply, and GST at 18 per cent is added to the fee and the interest. The EMI is paid alongside the monthly card bill.
Is a part payment better than paying nothing at all?
It avoids the late payment fee and an entry in the credit record. It does not restore the interest-free period for that cycle. The remaining balance accrues finance charges from the transaction date.
Why does the calculator stop if principal does not reduce?
Under the RBI Master Direction, a minimum due that fails to reduce principal would be revised upward by a real card. The simulation stops at that point because continuing would misrepresent what a card would actually do. Raise the payment to see a complete run.
Does the page account for cash advances or late fees?
No. Cash advances carry interest from day one, often at a different rate, and carry no grace period. Late fees are flat charges that do not compound. Add both separately to the figures the page prints.
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