A card surcharge is an optional percent Rundoo tacks onto card-tender sales to recover processing fees, shown as a separate Card fee (N%) line on the sale and the receipt.
In the Admin mode, open the Communications tab. The Card payment surcharge section sits between Statements and Loyalty points.
Every card swipe, tap, or keyed-in charge costs the store a processing fee. A card surcharge is how Rundoo can pass a percent of that fee through to the customer when they pay with a card — it shows up as a Card fee (N%) line in the totals stack, calculated off the Sale total (subtotal + tax). Cash, check, and charge-account sales never see it.

The surcharge is a Company-wide setting (not per-location), and it only applies to the Card tender — not Gift card, not ACH, not custom clearing tenders. See Tender methods for the full tender catalog.
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Card surcharges are not legal in every US state. A handful of states (Connecticut and Massachusetts at last check, with others evolving) prohibit them outright; others require specific signage or cap the percentage. Verify with your jurisdiction and card-network rules before turning this on — you're responsible for compliance, not Rundoo.
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Surcharges are off by default — the rate input starts at 0, which means no Card fee line ever renders. Turning them on is just setting a non-zero percent.

Two controls in the section:
Card surcharge (%) — the percent Rundoo applies to card sales. Typical values are 2 or 3 depending on what your processor charges. The input is capped between 0% and 4% — higher than 4 isn't supported. Setting it back to 0 disables surcharges entirely without having to clear anything else.Apply sales tax to card surcharge — a toggle that decides whether the surcharge itself gets taxed. Off by default (the surcharge is a fee, not a taxable sale of goods), but some jurisdictions require it on. Check with your accountant or tax authority before flipping this.Click Save when you're done. Changes take effect on the next sale — in-flight carts keep their current calculation.
Once a non-zero rate is set, every cart shows a Card fee (N%) line in the totals stack at the bottom-right of the Transaction-builder, between Sales tax and Sale total.

A few things worth knowing about how this feels at the counter:
Card fee (N%) is a per-sale override. It's checked by default whenever the cart will likely settle on Card. A cashier can uncheck it to waive the surcharge for a specific sale (say, a debit-card sale where you don't want to charge the fee, a customer who complained, or a trade partner getting a courtesy). Unchecking updates the Sale total immediately. This per-sale toggle is your lever for jurisdictions that restrict surcharges on specific tender types.