Honestly, been using credit cards for about 9 years now across HDFC, SBI, and Axis — and I've never paid a single rupee in interest. Here's exactly how it works.
The only real rule is: pay the full statement balance, every single month, before the due date. That's it. No trick, no setting, no hack.
But the thing most people get wrong — and what happened to you — is paying only the minimum due. Banks show that number very prominently because it's great for them. When you pay minimum, two things happen. One, you lose the interest-free period completely, so even new purchases from the next day start attracting interest immediately. Two, the interest is calculated on the original full outstanding amount, not just what's left. HDFC typically charges around 3.49% per month, which is almost 42% annually. That's brutal.
Here's what you do going forward:
First, set up autopay for the full statement amount. Not minimum due, not a fixed amount — full statement balance. HDFC NetBanking lets you set this up under the credit card section. Takes 5 minutes. This alone will save you from ever repeating this mistake.
Second, treat your credit card limit like it doesn't exist. Only spend what you already have in your savings account. If you don't have ₹3000 in your account, don't spend ₹3000 on the card.
Third — about EMI conversion — yes this does affect things but differently. If you convert a purchase to EMI after the fact, that amount is usually removed from your revolving balance, so it can actually help in some situations. But the EMI itself has its own interest rate (usually 12-18% per annum), so it's not free either. Only use EMI for large planned purchases, not to manage overspending.
For your current situation: pay off the entire outstanding amount this month, including whatever interest has been charged. Don't let it carry forward. One more month of minimum payment and you'll be in a worse spiral.
Also check if HDFC gave you a credit shield or any waiver option — sometimes for first-time customers they waive one instance of interest if you call and ask nicely. Worth trying.
Go set up that autopay today.