Bill by the hour, the day, or the retainer — this template handles all three. Clean typography and clear engagement references make it easy for your client's accounts payable team to approve and pay without questions.
| Description | Qty | Rate | Amount |
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Three common models: hourly (hours × rate), daily (days × day rate), or a monthly retainer as a single line. Retainers can include an hours allowance — list overage hours as a separate line so the client sees exactly what's inside and outside the retainer.
A PO or engagement reference on the invoice, your payment details, an itemized breakdown that matches the contract, and a due date that matches their payment cycle (Net 15 or Net 30). Clear invoices get through accounts payable without back-and-forth.
Either works — many consultants bill fees and billable expenses on the same invoice as separate lines, marked "at cost". Note your expense policy in the terms so there are no surprises.
Consulting is billed by hour, by day, by retainer or by project — and the invoice should read exactly like the contract sounds. If your engagement letter says "$5,000 monthly retainer including up to 20 hours", the invoice is one retainer line plus a separate line for any hours beyond 20. If it says "$1,750 per day on-site", the invoice lists days with dates. The AP clerk matching your invoice to the contract should find a one-to-one mapping, not a puzzle.
Bill expenses either at cost with receipts available on request, or with a stated administration margin — but pick one policy, write it in the engagement letter, and apply it identically on every invoice. List expenses on separate lines below fees, never buried inside a fee line.
For travel-heavy engagements, many consultants invoice expenses monthly and fees on a different cycle; that's fine, just keep both series of numbers distinct and referenced to the engagement code.
A retainer month with overage hours and pass-through expenses:
The PO reference gets the invoice past intake; the retainer/overage split matches the contract language; expenses sit on their own lines at cost. Nothing for accounts payable to question — which is exactly the point.