Credit card interest is quoted per month, so it looks small: 3 or 4 per cent. Two things make it much bigger in practice. It compounds on the whole outstanding every month you carry a balance, and GST at 18% is charged on top of the interest itself. Most interest sheets leave out the GST and stop at one month. This one runs the balance month by month, up to 30 years, for your own payment and for paying only the minimum due.
Download: Credit card interest calculator (.xlsx, free)What the sheet does
- Takes your outstanding balance, the card's monthly interest rate, GST, and what you plan to pay each month.
- Builds two month-by-month tables side by side: your plan, and minimum due only (5% of the outstanding with a ₹200 floor, both editable).
- Shows the months to clear and the total interest plus GST for each, and how much your plan saves.
- Warns you when your payment doesn't even cover the first month's interest and GST, so the balance would grow.
- A plain .xlsx with live formulas and no macros, licensed CC BY 4.0.
₹1 lakh at 3.75% a month, worked through
- With 18% GST on the interest, the effective monthly cost is about 4.4% of the outstanding.
- Paying ₹5,000 a month clears it in 50 months, with about ₹1,49,760 paid in interest and GST on top of the ₹1 lakh.
- Paying only a 5% minimum due barely covers that 4.4%, so the balance shrinks very slowly: after 30 years it is still not cleared, and interest plus GST paid has passed ₹6.7 lakh.
Rates differ by card and by how you use it, so type the rate from your own card's MITC, the document that lists its charges. The pattern holds at any rate: the closer your payment is to the minimum due, the longer the debt lasts and the more of every payment goes to interest.
Card or personal loan? Compare the real costWhat the sheet does not do
- It assumes no new spending on the card while you repay.
- Late-payment fees and their GST are not included; a missed due date adds those on top.
- Some banks set the minimum due differently (for example a percentage plus all interest and taxes); change the minimum cells to match your statement.
Frequently asked questions
- How is credit card interest calculated in India?
- On the outstanding balance at the card's monthly rate, usually 3–4%, every month you carry a balance, with 18% GST charged on the interest. The sheet applies both, month by month.
- Is GST charged on credit card interest?
- Yes, GST at 18% applies to the interest and to fees, which raises the effective monthly cost above the quoted rate.
- What happens if I pay only the minimum due?
- Most of the payment goes to interest and GST, so the balance falls very slowly. On ₹1 lakh at 3.75% a month, a 5% minimum does not clear it even in 30 years.
- Does the sheet work in Google Sheets?
- Yes. Upload the .xlsx to Google Drive and open it with Google Sheets; the formulas carry over.