You gotta hand it to carriers: if there’s a way to squeeze an extra few dollars out of their customers, they will find it. As reported by The Wall Street Journal, the latest maneuver is requiring customers — current and new — to switch to a debit card or bank account withdrawal in order to receive the autopay discount on their plan. Verizon has included this requirement on plans for years, but in the past few months, AT&T and T-Mobile have quietly followed suit to cut back on how much they pay for credit card processing.

The new rule goes into effect for AT&T customers on October 2nd, and as a gesture of goodwill, the company will only reduce your discount if you continue to pay with a credit card. Those who register for autopay with a bank or debit card will receive $10 off; a credit card will only get you $5. T-Mobile’s change went into effect in July, also eliminating Apple Pay and Google Pay as methods eligible for the $5 discount. Oh, and technically, you can qualify for Verizon’s autopay discount with a credit card — it just has to be a Verizon Visa card.

AT&T and T-Mobile aren’t just making this a requirement for new customers — the change is being applied to all postpaid accounts. Even if you’ve been receiving the discount for years with a credit card, you’ll have to make the switch in order to keep your discount. And it adds up — the discounts are applied for each line on your plan, so if your whole family is on the same plan, it’s a significant amount of money.

As far as nefarious carrier maneuvers go, this one is at least somewhat understandable. Credit cards charge businesses high processing fees, and those rates have been rising. But even with the new rules in effect, carriers continue to advertise their plan pricing with the autopay discount factored in. As always, you have to read the fine print to see what they’re really up to.