Payment processing is the arrangement that lets a business accept card and electronic payments.
What it costs
A percentage of each transaction plus a fixed amount, varying by card type and by whether the card was present. Card-not-present rates are higher.
At scale this is a meaningful cost against gross margin and belongs on its own line — see bank and merchant fees.
Why it is generally worth paying
Days to get paid falls sharply when payment can be taken at completion rather than invoiced and chased.
A processing fee of a few per cent against an invoice paid immediately usually compares well with the same invoice paid in six weeks after two reminders — see collections.
Bank transfer
Direct bank payment costs materially less than card and settles more slowly. For larger invoices the saving is significant enough to be worth offering as the preferred option.
Surcharging
Passing the card fee to the customer is permitted in some states and prohibited in others, and where it is permitted it carries disclosure requirements. Offering a discount for other payment methods is treated differently from adding a surcharge, and is more widely allowed.
Worth confirming locally before implementing.
Holds and reserves
New accounts, and businesses taking large deposits for work delivered later, are commonly subject to holds or rolling reserves. Money taken is not always money available immediately, which matters to a cash flow forecast.
Disputes
A customer can reverse a card payment after the fact — see chargebacks.