Man, you hit the nail right on the head—this is a huge headache that trips up so many guys in the trades. software companies love to tell you to "just add a line item," but they completely ignore the legal landmine they're handing you when the checkout system can't tell a debit card from a credit card.
Credit card networks and federal law explicitly prohibit putting a surcharge on debit cards, even when they're run as credit without a PIN, and credit card surcharges themselves are capped at actual processing costs.
When a platform doesn't have card-type detection built into the checkout screen to catch this automatically, throwing a flat processing fee line item on an estimate or invoice leaves you wide open to merchant agreement violations the second a customer pays with a debit card or bank transfer.
To dodge that mess, a lot of guys switch over to a cash or ACH discount setup. You set your standard pricing to cover the card fee, then offer a discount if they pay by check, cash, or bank transfer. Card brand rules explicitly allow that, and it gets you around the debit card surcharge traps entirely.
Another way to handle it is dual pricing, where you state the terms upfront but only attach that fee line item after the client confirms they are using an actual credit card.
Otherwise, plenty of contractors just bake a couple percent right into their overall overhead and job margins. It stings a little to absorb it, but it completely removes the headache, customer pushback, and compliance risk.
