Consulting Invoice: How Consultants Bill Clients (With Examples)

Consultants tend to bill in one of four ways (hourly, daily, by project or by retainer) and often to organisations with formal purchasing processes. The invoice needs to be precise and match what the client's procurement team approved.

What a consulting invoice should include

• Your name or firm name, address, email, tax number if registered
• The client's legal entity name and billing address (large companies often have several entities; use the one in your contract)
• PO number, contract number or statement of work reference
• Invoice number, date, due date
• The engagement: project name and period covered
• Fees, itemized
• Expenses, itemized and supported
• Tax, if applicable
• Payment details

Day rates

Common in management and IT consulting.

Description	Days	Rate	Amount
Operations review, phase 1: on-site workshops and analysis (1–12 Sept)	8	$1,200.00	$9,600.00
Final report and presentation to leadership (15 Sept)	1.5	$1,200.00	$1,800.00
Fees subtotal			$11,400.00

Define what a "day" means in your contract (commonly 7.5 or 8 hours) and how partial days are billed.

Hourly

Better for advisory work in smaller increments. Summarize by activity:

Description	Hours	Rate	Amount
Pricing strategy advisory calls (4 sessions)	5.0	$220.00	$1,100.00
Competitor pricing analysis and memo	6.5	$220.00	$1,430.00

Project fees

Invoice by milestone as defined in the statement of work:

Milestone 2 of 3: market entry assessment delivered 5 September 2026 (per SOW-004): $15,000.00

Retainers

For ongoing advisory relationships:

Advisory retainer, October 2026 (up to 10 hours; see agreement dated 1 July 2026): $2,500.00

Say whether unused hours roll over (usually not) and how overage is billed. See retainer invoices.

Expenses

Corporate clients often have specific expense policies: economy flights, hotel caps, per diems, receipts over a certain amount. Follow them exactly, or expect expenses to be rejected.

Description	Amount
Flight, Chicago–Denver return, 1–3 Sept (receipt attached)	$412.00
Hotel, 2 nights (receipt attached)	$356.00
Ground transport	$84.50
Expenses subtotal	$852.50

Many consultants list expenses at cost with no markup to keep things simple. If you mark up, your contract should say so.

Working with procurement

Large organisations may require you to:

• Register as a supplier before your first invoice (tax forms, bank verification, insurance certificates)
• Submit invoices through a supplier portal rather than by email
• Quote a PO number on every invoice, with amounts that stay within the PO
• Accept their payment terms (Net 45 or Net 60 is common)

Ask about all of this at the start. It's much faster to set up during contracting than after you've done the work. See PO numbers on invoices.

Payment terms

Try to negotiate terms in the contract, not on the invoice. If a client's standard is Net 60, options include a mobilisation fee upfront, monthly invoicing (so the gap never gets too large), or a slightly higher rate that reflects the delay.

Tax notes

• US: consulting services are generally not subject to sales tax, though a few states tax certain professional services.
• UK: VAT applies once you're registered; for business clients abroad, the service is often outside the scope of UK VAT under place-of-supply rules.
• EU: cross-border B2B consulting usually falls under the reverse charge, with the customer's VAT number and "Reverse charge" on the invoice. See invoicing international clients.