What Is an Add-On (Supplementary) Credit Card?
One account, a second physical card
An add-on card, also called a supplementary card, is a second card issued on your existing credit card account, typically for a spouse, parent, or adult child. It carries the add-on holder's own name and often its own card number, but it draws from the same overall credit limit as your primary card, not a separate one.
Who's actually responsible for the bill
You are, entirely. The primary cardholder is legally liable for everything charged on every add-on card linked to the account, the add-on holder isn't billed separately and generally has no direct payment obligation to the bank. If an add-on card is misused or overspent, it's your credit score and your repayment obligation on the line, not theirs.
What that liability actually looks like
Say your add-on holder spends ₹35,000 in a month without telling you, on top of your own ₹20,000, for a combined ₹55,000 statement. The bank sees one account and one Total Amount Due, ₹55,000, with your name on it. If it isn't paid in full, the finance charges, the late fee if it comes to that, and the credit bureau reporting all attach to your credit profile, not a separate record for the add-on holder. There's no mechanism for the bank to split responsibility after the fact, which is why this is worth an honest conversation about spending limits before handing someone an add-on card, not after a surprising statement shows up.
What add-on holders can and can't do
They can spend up to the shared credit limit, and in most cases earn reward points the same way a primary transaction would, credited to the main account. What they typically can't do is manage the account itself: setting the credit limit, requesting a limit increase, or closing the account are usually primary-cardholder-only actions, though some banks let you set a separate, smaller spending limit specifically for an add-on card if you want tighter control.
Why people actually get one
The common reasons are practical rather than about extra spending power: giving a non-earning spouse a card of their own without opening a separate account, letting a young adult child build transaction history before they're eligible for a card in their own name, or simply having a backup card under a trusted person's control for emergencies. If that young adult would rather start building their own independent credit history instead of riding on yours, a card secured against a fixed deposit is usually the more direct route. Since an add-on remains your liability either way, it's worth treating the request with the same trust threshold you'd apply to handing someone your primary card.
