Every other business in this series has one kind of card money. A law firm has two, and they are not allowed to mix. An invoice for work already done is the firm's money and belongs in its operating account. A retainer for work not yet done is the client's money, held in trust, and it belongs in the trust account until the work is performed and billed. A payment setup that gets that routing wrong is not a bargain at any rate — it is a compliance problem with a processing fee attached. So this guide starts with the routing, and only then talks about price.
The rules and product descriptions below are general information drawn from a provincial law society's published trust guidance and from legal-payments providers operating in Canada — not legal advice, and not a substitute for your own law society's rules, which govern your practice. Rates were checked on 2026-10-15 from the sources named in the table, and the worked example is an illustration built from those published rates.
Two kinds of money: earned fees and trust retainers
The Law Society of Ontario's trust account decision tree states the sequence plainly. If legal services have not been performed, funds received from a client go into the trust account. Once the services have been performed and a bill has been delivered to the client, the billed amount — and only the billed amount — is transferred from trust to the general account, any remaining trust funds stay in trust, and the recordkeeping requirements for both accounts apply throughout. Money received for services already performed and billed follows the other path, into the operating account as the firm's own funds.
Card payments complicate that sequence in one specific way: a card transaction is not a single movement of money. There is the amount the client authorizes, the amount that is deposited, and the processing fee — and if the fee is simply deducted from the deposit, a retainer that should arrive in trust whole arrives short. On a trust deposit, short is not a rounding issue. The client was told a specific sum is held for them, the trust ledger records that sum, and the account has to be able to show it. That is why, for law firms, where the fee comes out is a first-order product feature, ahead of what the fee is.
The trust test every processor has to pass first
Legal-specific payment products are built around exactly this point. Clio, whose payments product is available to Canadian firms, describes the mechanics this way: payments are directed automatically into the correct trust or operating account, earned and unearned fees are always kept separate, and processing fees are never debited from trust accounts. Its help centre adds the chargeback half of the design — when a client disputes a card payment, the disputed amount and the chargeback fee are withdrawn from the firm's operating account even when the original payment was made into trust, so a dispute never pulls client trust funds back out. In Canada that chargeback fee is $20 per dispute, applied regardless of the outcome.
Helcim approaches the same problem from the general-processor side: its law-office page describes interchange-plus pricing with no monthly fee and no setup, termination, quarterly, PCI, customer-service, or bank-deposit fees, and tools designed to simplify trust accounting and client billing. A general processor can be used compliantly — firms did it long before legal-specific products existed — but the separation then lives in the firm's own procedures and account setup rather than in the product: trust deposits must be directed to the trust account, fees must be settled from operating, and every transfer from trust to operating still waits for a delivered bill. Whichever route a firm takes, the test questions are the same, and they come before the rate card: Can trust and operating be separated at the point of payment, not by a manual fix afterward? Are fees and chargebacks structurally barred from the trust account? Does the record produced by a payment match what trust bookkeeping has to show?
The rates on the table, checked 2026-10-15
| Option | Online / invoice rate | In-person | Trust handling (as described by the provider) |
|---|---|---|---|
| Helcim (interchange-plus; published averages) | 2.31% + 25¢ average | 1.79% + 8¢ average | Tools described as simplifying trust accounting and client billing; no monthly fee |
| Square (flat rate, general processor) | 2.8% + 30¢ card-not-present · 3.3% + 15¢ keyed | 2.5% per credit transaction | No legal trust routing described; separation is the firm's own procedure |
| Stripe (online, general processor) | 2.9% + CA$0.30 domestic | — | No legal trust routing described; separation is the firm's own procedure |
| Clio Payments (legal-specific) | Rate not published in the sources checked for this guide — confirm directly | Available online and in person in Canada | Automatic trust/operating direction; fees never debited from trust; Canadian chargeback fee $20, taken from operating |
The empty cell in that table is deliberate. Clio describes transparent per-card-type pricing with no per-transaction fee in its comparison material, but no Canadian rate was published in the sources checked on 2026-10-15, so no rate is printed here and Clio is excluded from the worked math rather than assigned an invented number. That is the correct treatment for any legal-specific product a firm is quoted: get the rate in writing, then run it through the same arithmetic as the published options. Note also that interchange-plus options pass through the federal small-business interchange reductions — up to 27% for eligible businesses, to a weighted in-store average of 0.95% — automatically, while a flat rate changes only when the provider changes it.
Worked math: $50,000 a month of invoices and retainers
The illustration: $50,000 a month collected by card online — $30,000 of earned-fee invoices (20 payments averaging $1,500) paid into operating, and $20,000 of retainers (8 payments averaging $2,500) paid into trust. Twenty-eight payments in total. Processing only; software subscriptions and taxes excluded.
Helcim at its published online average: $50,000 × 2.31% = $1,155.00, plus 28 × 25¢ = $7.00. Month: $1,162.00 — with every dollar of that fee settled from operating, never netted against the trust deposits.
Square card-not-present: $50,000 × 2.8% = $1,400.00, plus 28 × 30¢ = $8.40. Month: $1,408.40.
Stripe online: $50,000 × 2.9% = $1,450.00, plus 28 × CA$0.30 = $8.40. Month: $1,458.40.
The gap: about $246 to $296 a month between the published interchange-plus average and the general flat and online rates — roughly $3,000 to $3,550 a year on this volume. Whether that gap justifies a general processor depends entirely on whether the firm can run the trust separation itself, reliably, every payment, including the awkward ones.
The $2,500 retainer, cent by cent
Take one retainer of $2,500 paid by card at the published online average of 2.31% plus 25¢. The processing fee is $57.75 plus $0.25 — $58.00. The client authorized $2,500 to be held in trust, so $2,500 is what the trust account must receive and what the trust ledger must show. The $58.00 is a cost of the firm's decision to accept cards, and it is paid from the firm's operating account. If instead the fee were netted from the deposit, trust would hold $2,442.00 against a $2,500 obligation — a shortfall created by the payment method, sitting in the one account where a firm can least afford unexplained differences. This is why legal-specific products make a point of never debiting fees from trust, and why a firm on a general processor has to confirm, in writing, exactly how its fees are settled before the first retainer is taken by card.
The same discipline governs the way out. When the work is done and a bill is delivered, the billed amount moves from trust to operating — not the amount the firm hopes to bill, and not before the bill exists. A payment platform that records the payment, the matter, and the account it landed in gives the bookkeeper a trail that matches that sequence; a platform that simply deposits money forces the trail to be rebuilt by hand, which is where trust accounting errors are actually born.
Chargebacks and surcharging: where firms get caught
A chargeback on a legal payment is worse than the fee, which in Canada is $20 per dispute on Clio Payments regardless of outcome. The disputed amount comes back out — from operating, on a properly separated setup, even if the original payment went into trust — the bill returns to unpaid, and the firm is suddenly re-litigating whether it was paid at all, on a matter where its own records have to be impeccable. Large retainers taken by card from new clients deserve the same care as any other trust receipt: confirm identity and authorization, document the retainer agreement, and treat an unusual card-funded retainer as a reason to slow down, not speed up.
Surcharging clients for card use needs even more restraint. Mastercard's Canadian rules cap a credit surcharge at 2.4% and at the merchant's cost of acceptance, require clear disclosure at the point of interaction and on the receipt, and state that provincial and federal law is unaffected. For a firm, the network cap is only the first question: professional-conduct and fee rules, the terms of the retainer agreement, and the special character of trust money — where adding a fee changes what a client must pay to place an exact sum in trust — all sit on top of it. Many firms will conclude that absorbing the fee on trust deposits and pricing it into their fees is the defensible course. Either way, it is a decision to take with the firm's own law society guidance in hand, not a toggle to enable in a payments dashboard.
Decision framework: legal-specific or general processor
- Routing before rates. Require, in writing, that trust deposits land in trust whole, and that all fees and chargebacks settle from operating. A product that cannot promise that is not cheaper — it is disqualified.
- Price the firm's real mix. Separate earned invoices from retainers for one month and run the worked-math method. Invoice volume usually dominates the rate comparison; retainers dominate the risk comparison.
- Demand the unpublished rate in writing. Legal-specific pricing that is not published can still be competitive — but only a written rate can be compared, and only a written rate can be held to.
- Walk the chargeback path before it happens: which account is debited, what fee applies, what record is produced, and who at the firm is notified.
- Decide surcharging as a professional-conduct question, with your law society's current guidance and your retainer wording in front of you — not as a processing feature.
A note on steps: this is a pricing and decision guide, not a compliance procedure, so the framework above is the actionable part rather than a numbered fix. Trust-account obligations themselves come from your law society, not from this page.
Disclaimer: general information about payment processing and published trust-account guidance only — not legal, financial, or accounting advice, and not a statement of any law society's current rules. Check your own regulator's requirements and confirm current pricing in writing before acting. Rates checked 2026-10-15.
FAQ
Can a client pay a retainer by credit card?
Card acceptance itself is a payments question; where the money must go is a trust question. Published Ontario guidance puts funds for services not yet performed into the trust account, with only the billed amount moving to the general account after services are performed and a bill is delivered. The processing setup has to respect that sequence — and your own law society's rules govern in your province.
Who should pay the processing fee on a trust deposit — the client or the firm?
The trust account must be able to show the full retainer the client placed. Legal-specific products therefore settle fees from the firm's operating account and never debit trust. Passing any fee to a client on top of a trust deposit raises surcharge, disclosure, and professional-conduct questions to settle with your regulator's guidance first — it is not a default setting.
What happens to trust money if a client charges back a retainer payment?
On Clio Payments, the disputed amount and the $20 CAD chargeback fee are withdrawn from the firm's operating account even when the original payment went into trust — the design exists specifically to keep a dispute from pulling client trust funds. On any other setup, ask the same question in writing before you need the answer.
Is a cheaper general processor worth it for a law firm?
On $50,000 a month of online collections, the published interchange-plus average worked out about $246 to $296 a month below Square's card-not-present and Stripe's online rates. That saving is real only if the firm can run trust/operating separation, fee settlement from operating, and the transfer-on-billing sequence flawlessly with its own procedures — the rate is the second decision, never the first.