Ontario Legal Fees and HST Calculator

The order of operations is the whole point of this tool. Amounts treated as incurred as agent are excluded from the HST base and added after tax; everything else is taxed. Putting an as-agent amount in the wrong column does not just move a line, it changes the tax.

Categories. The two disbursement columns use the CRA's agency framing: treated as incurred as agent, and treated as not incurred as agent. They are deliberately not labelled taxable and non-taxable. Whether a lawyer acted as agent for the client on a particular payment is a factual and legal question, and Policy Statement P-209R is general guidance rather than a ruling on your invoice. The same kind of expense can fall on either side depending on who the recipient of the supply was, how the payment was arranged and whether the amount was re-billed at cost.

Rate. 13% is the ordinary Ontario rate, which is why it is pre-filled. It is not automatic. Place-of-supply rules can point to another province's rate, some supplies are exempt or zero-rated, supplies to non-residents can be treated differently, and a supplier who is not registered does not charge the tax at all. Change the rate field where a different rate governs.

Rounding. The tool carries full precision through every step and rounds only when a figure is displayed to the cent. Adding up the displayed lines by hand can therefore differ from the displayed total by a cent. Accounting systems that round each line before totalling will produce that same one-cent variance.

• Professional fees and two separate disbursement columns using the CRA agency categories.
• A further non-taxable column for amounts that belong on the invoice but outside the tax base.
• An editable tax rate, so the calculation is not locked to 13%.
• HST calculated on the fees-plus-not-as-agent subtotal only, with the as-agent total added after tax.
• A retainer credit applied against the gross invoice, with any surplus shown as a remaining trust credit.
• A line-by-line breakdown you can compare against an invoice you have received or are preparing.

• Adding the as-agent disbursements into the subtotal before tax. That inflates the HST base and overstates the tax.
• Assuming a court filing fee is always as-agent. It often is, but how the payment was made and billed can change the treatment.
• Treating a re-billed expense with a mark-up as an as-agent pass-through. An amount re-billed above cost does not sit comfortably in that category.
• Applying the retainer before tax. The credit comes off the gross invoice, not the subtotal.
• Reading a remaining trust credit as money that has already been refunded. It is a calculated surplus, nothing more.
• Assuming 13% because the firm is in Ontario, without checking where the supply is treated as made.
• Chasing a one-cent difference between hand-added lines and the total. That is the rounding convention described above, not an error.

• Check each disbursement against the CRA guidance on lawyers' disbursements before deciding which column it belongs in.
• Confirm the rate against the CRA rate calculator and the place-of-supply rules for the services actually supplied.
• Confirm the invoice shows the information a registrant is required to provide, including a business number where required under current CRA invoice rules.
• Ask the firm to explain any line you cannot reconcile, rather than assuming this tool's categorisation is the one they used.
• Take professional tax or legal advice where the characterisation of a disbursement is genuinely uncertain, or where trust money is involved.

Legal information reviewed: 21 August 2026. Checked against the official sources listed on this page. Rates, fees and rules change; confirm anything you rely on.

Some of this calculation follows from how the tax works. The rest follows from decisions you made when filling in the form. Knowing which is which tells you where an invoice can properly be questioned.

The retainer is subtracted only after the invoice and its tax have been calculated, and the figure to enter is the retainer still available on the trust ledger, not the amount originally received. Where the available retainer exceeds the invoice, the surplus is shown as an unapplied retainer balance. That is an arithmetic remainder. It is not a finding that the money is refundable, that it may be transferred out of trust, or that any billing or trust-accounting requirement has been met. Those are governed by the Law Society's requirements for trust account operation and for fees and disbursements, linked below.

• Clients: work down the invoice line by line and ask which disbursements were incurred as agent and why, rather than asking whether the total looks right.
• Clients: check the retainer figure against the statements of account you have received, and ask for the trust ledger if the running balance is unclear.
• Firms: keep the classification reasoning on file for the disbursements that could plausibly sit in either column, because the label alone will not support it later.
• Both: where the rate is in question, resolve the place-of-supply analysis before arguing about the arithmetic.
• Both: raise a discrepancy in writing while the account is current. Questions about a lawyer's account have their own procedures and time limits, none of which this tool addresses.
• Read the companion guides for the tax mechanics and for a structured read-through of an invoice you have received.

Checked on 21 August 2026 against CRA Policy Statement P-209R on lawyers' disbursements, CRA GI-197 on out-of-pocket expenses, the CRA place-of-supply guidance, and the Law Society of Ontario's practice resources on HST, trust accounts and bookkeeping and fees and disbursements. CRA policy statements state general administrative positions rather than law, and both they and the LSO resources are revised from time to time.

At this review the worked examples were replaced with three that turn on classification rather than on different numbers, and the fixed-rules table, retainer section, next steps and this note were added. The engine is unchanged: taxable base of fees plus not-as-agent disbursements, tax on that base at the rate you enter, as-agent amounts added after tax, and the available retainer applied to the total.