Is it worth taking card payments for professional services?

For most professional firms the honest answer is yes — on the right invoices. A card fee of 1.5–3% is real money, but on small and recurring invoices it buys the thing your cash flow actually lacks: payment now, from a client who was always going to pay eventually, but slowly. The craft is knowing which invoices deserve which rail.

Accountants, consultancies and law firms are the last industries where “send an invoice, wait for a transfer” is still the default — and it shows in the debtor days. Meanwhile the operators who’ve switched describe the change simply: “sending customers invoices and they pay via a link.” Here’s the maths, the rail-by-rail split, and the reconciliation catch nobody mentions until month-end.

The fee is the wrong number to stare at

The instinct is to compare the card fee with zero, because bank transfers are “free.” But a bank-transfer invoice isn’t free — it pays in days-to-weeks, it needs chasing, and every chase is partner or admin time. The real comparison is:

• Card on a payment link: ~1.5–3% fee, paid in seconds, zero chasing, self-reconciling.
• “Free” bank transfer: £0 fee, plus the overdraft cost of waiting, plus the admin cost of chasing the ones that go late, plus the deposits you can’t match at month-end.

On a £600 monthly bookkeeping retainer, a card costs under £20. If the alternative is the invoice aging two or three weeks — and one in ten needing a chase cycle — the card is cheaper the moment you price your own time above zero. On a £45,000 corporate-finance fee, the same percentage is £900+ and the calculus flips completely: big invoices have their own maths.

The three-rail split most firms land on

Payment links (cards + Apple Pay / Google Pay) for everything small. A link on the invoice opens a checkout for exactly that invoice; the client pays in three taps from a phone. No developer, no typing account numbers into a banking portal — which matters, because friction is the single biggest predictor of a late invoice. Use it for anything up to a few thousand.

Direct debit for retainers and recurring compliance work. For monthly fees, pull beats push: a direct debit mandate (or ACH authorisation in the US) collects on schedule at a flat, low cost, and removes the “client forgot” failure mode entirely. Recurring billing that raises, collects and reconciles itself is the closest thing to not having debtors at all.

Bank transfer for the large one-offs. Above a few thousand, the percentage fee stops being trivial and clients’ AP processes expect a transfer anyway. Keep it — but still put the amount, reference and your details in a structured invoice so it reconciles cleanly.

The principle in one line: make the easiest method the default where its fee is trivial, and keep the free rail where the fee would sting.

The catch: cards taken beside the invoice don’t reconcile

Here’s the part that bites at month-end. A card payment taken through a standalone terminal or a generic checkout is an anonymous deposit — right amount, wrong metadata — and someone matches it to an invoice by hand. Multiply by a client base and you’ve traded debtor days for a reconciliation backlog.

The fix is structural: take cards through the invoice, so the payment is born knowing which invoice it belongs to. That’s how Fynex runs it — every invoice carries a branded link, every payment books itself to Xero or QuickBooks with the fee split out, and the recurring retainers raise, collect and reconcile themselves. The awkward “just following up” email gets sent by an agent on the days you’d rather not think about it.

What this looks like in a real firm

A practice with 80 clients might run: retainers on direct debit (collected on the 1st, reconciled automatically), ad-hoc advisory invoices under £2,000 on payment links (most paid same-week), and the handful of large transactional fees on bank transfer with agentic chasing behind them. Debtor days fall not because clients changed, but because the easy path and the paid path became the same path.

Is it worth adding card payments to your invoices? For the invoices where the fee is coffee money and the delay is the real cost — yes, and it’s probably overdue. Keep the transfer rail for the big fees, put a link on everything else, and let the reconciliation happen where it should: nowhere you can see it.