A retainer gives you predictable income and the client predictable access, and it is easier to defend than a fluctuating hourly bill. Many consultants run a retainer for the baseline and hourly for anything beyond it — which this template shows on one document.

What terms do consultants normally use?

Net 30 with corporates, and expect it to mean 45 in practice. Retainers are often invoiced in advance for the coming month rather than in arrears — worth agreeing in writing before the first invoice.

How do I bill for travel time?

Either at a reduced hourly rate or as a flat fee per trip, agreed up front. Billing travel at your full rate is defensible but frequently disputed, so say which it is before you invoice it.

Should I show my hourly rate on a fixed-fee invoice?

No. If you agreed a fixed fee, invoice the fixed fee. Showing the hourly maths invites a negotiation about hours you already agreed not to have.

Should I invoice a retainer in advance or arrears?

In advance is standard for retainers, because the client is buying access and availability rather than a delivered artefact. Project work is normally invoiced in arrears or against milestones. Whichever you choose, agree it in writing before the first invoice — it is a common source of friction precisely because both conventions exist.

Invoice Builder › Consultant

Consulting invoice template

Set up for corporate billing, where the invoice has to survive an accounts payable system: a purchase order field, clear period covered, and expenses separated from fees.

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INVOICE

Invoice # Date Due PO / Ref

From

Bill to

Description	Qty / Hrs	Rate	Amount

Subtotal$0.00

Discount % $0.00

Tax % $0.00

Shipping

Total$0.00

Amount paid

Balance due$0.00

Notes

Terms & payment details

How to bill for consultant work

Always get the PO number first

Large companies reject invoices without one, and the rejection is frequently silent. Ask for it before the work starts, and put it in the PO field.

State the period the work covers

'Retainer — March 2026' in the description. Accounts teams reconcile by period, and an invoice they cannot place is an invoice that waits.

Bill expenses at cost, on their own line

Marking up travel is the fastest way to make a client audit everything else on the invoice.

What belongs on a consulting invoice

The purchase order number — most large companies reject invoices without one
The period the work covers, stated explicitly (for example 'March 2026')
Retainer and additional hours as separate lines
Day rates and hourly rates shown distinctly if you use both
Expenses at cost, itemised, with receipts referenced
Your company registration and tax numbers
The name of the engagement or statement of work it falls under

Common questions

Retainer or hourly?: A retainer gives you predictable income and the client predictable access, and it is easier to defend than a fluctuating hourly bill. Many consultants run a retainer for the baseline and hourly for anything beyond it — which this template shows on one document.
What terms do consultants normally use?: Net 30 with corporates, and expect it to mean 45 in practice. Retainers are often invoiced in advance for the coming month rather than in arrears — worth agreeing in writing before the first invoice.
How do I bill for travel time?: Either at a reduced hourly rate or as a flat fee per trip, agreed up front. Billing travel at your full rate is defensible but frequently disputed, so say which it is before you invoice it.
Should I show my hourly rate on a fixed-fee invoice?: No. If you agreed a fixed fee, invoice the fixed fee. Showing the hourly maths invites a negotiation about hours you already agreed not to have.
Should I invoice a retainer in advance or arrears?: In advance is standard for retainers, because the client is buying access and availability rather than a delivered artefact. Project work is normally invoiced in arrears or against milestones. Whichever you choose, agree it in writing before the first invoice — it is a common source of friction precisely because both conventions exist.