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Legal Billing Tool

Assemble an invoice from time, flat fees and expenses with discount, tax and retainer applied, whatever the practice area.

Last reviewed

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Free · No sign-up · Runs in your browser

Every legal invoice has the same components regardless of practice area: time, any fixed element, expenses, whatever concession was applied, tax where it applies, and client funds drawn down against the total.

This tool assembles them in that order and reports both the invoice total and the amount actually due, so the two are never conflated on the document a client receives.

Your numbers

Results update as you type. Nothing is sent anywhere.

Result

Invoice total

$4,989

Amount due

$1,989

Time fees
$4,620
Flat fee
$0
Discount
$231
Net fees
$4,389
Expenses
$600
Tax
$0
Retainer applied
$3,000
Credit remaining
$0

This tool performs arithmetic on the values you enter. It does not provide legal advice and does not create an attorney-client relationship.

Showing the discount as a separate line makes the concession visible to the client rather than hiding it in a lower rate.

Tax treatment of legal fees and of disbursements differs by jurisdiction. Confirm which lines are taxable where you practise.

How to use the legal billing tool

  1. Enter billable hours and the rate, plus any flat fee element.
  2. Add expenses and disbursements.
  3. Enter a discount percentage and the tax rate where one applies.
  4. Enter the retainer being applied and read the amount due.

What people use this for

  • Building an invoice before entering it into a billing system.
  • Checking what a client owes after client funds are applied.
  • Reconciling a matter that mixes fixed fees and hourly work.
  • Showing a discount as a visible concession rather than a hidden one.

Worked examples

Every figure below is produced by running this calculator against the example inputs, so the numbers always match the tool.

Time plus expenses with a retainer

14 hours at $330, $600 of expenses, a 5% discount and $3,000 of retainer applied.

Invoice total
$4,989
Amount due
$1,989
Discount
$231

A fixed fee with out-of-scope time

A $2,800 fixed fee plus 4 hours of additional work, with no retainer.

Invoice total
$4,440
Amount due
$4,440
Time fees
$1,320

Keep the retainer separate from the fees

Applying client funds reduces the amount due; it does not reduce the amount billed. Combining the two produces an invoice where neither figure can be traced, and makes trust ledger reconciliation harder than it needs to be.

Showing the total, then the funds applied, then the balance keeps the client-money position legible - which matters, because how those funds are held is a regulated question in most jurisdictions.

A discount shown is a discount valued

A reduction delivered by quietly removing recorded hours is invisible to the client and therefore earns nothing. The same reduction as a discount line is a visible decision.

It also protects the rate: a discount applies to one invoice, whereas a quietly reduced rate becomes the expected rate on every invoice afterwards.

Methodology and assumptions

What this calculator does, and what it deliberately does not do.

  • Time fees are hours × rate. The discount applies to fees only, not to expenses.
  • Tax applies to net fees plus expenses; which components are taxable differs by jurisdiction.
  • The retainer is applied last against the invoice total, with any excess reported as remaining credit.
  • The tool performs arithmetic or date counting on the values you enter. It does not interpret a rule, a statute or a contract.
  • Nothing you type is transmitted or stored - the calculation runs entirely inside your browser.

This website provides general informational and productivity tools and does not provide legal advice or create an attorney-client relationship.

The date and deadline tools count days exactly as you instruct them. They do not interpret court rules, statutes of limitation, filing requirements or any other legal authority, and they do not know the rules of your jurisdiction.

Always verify any date, fee, or calculation against the governing rule, the court calendar and your own professional judgement. If you need legal advice, consult a lawyer licensed in your jurisdiction.

Frequently asked questions

Does tax apply to disbursements?

It depends on the jurisdiction and whether the disbursement was incurred as agent or principal. Confirm the treatment where you practise.

Is this a compliant invoice?

No. Invoice content requirements differ by jurisdiction and frequently prescribe narrative, tax and regulatory details. This calculates amounts.

What if the retainer exceeds the invoice?

The applied amount is capped at the total and the remainder is reported as credit, which is how a trust ledger would treat it.

Can I use this outside law?

Yes. Any professional service billing time plus expenses against a deposit uses the same structure.

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