How do consultants invoice clients?

List your hours or project fee with rates, add expenses if any, include your details and the client’s, set net terms, and send a PDF.

Do I need a PO number on a consultant invoice?

For enterprise and government clients, almost always — their accounts-payable systems match invoices to purchase orders and auto-reject anything without a valid PO. Get the PO number before you begin work and put it on every invoice for that engagement. Small clients usually don’t use POs, so a clear reference to your proposal is enough.

Should consultants bill hourly or by project?

Project or milestone fees are easier to sell to executives and reward you for efficiency; hourly protects you when scope is genuinely open-ended. Many consultants use a paid discovery phase to scope the work, then a fixed-fee proposal for delivery. Whichever you choose, the invoice should trace back to the agreed basis in the SOW.

Free Consultant Invoice Template

Invoice consulting work professionally: bill by the hour or by project, add tax and payment terms, and download a polished PDF. Your details save in your browser.

Your business

Logo

Upload logo

Business name

Address

Phone

Tax ID

Website

Bill to

Client name

Address

Tax ID

Invoice details

Invoice #

Issue date

Due date

Currency

PO number

Items

DescriptionQtyRateAmount

Tax & totals

Tax label

Tax rate %

Tax inclusive

Discount

Discount value

Shipping

Amount paid

Notes & payment

Notes

Terms

Payment details

Style

Document type

Template

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What to include on a consulting invoice

A reference to the engagement or statement of work
Hours worked at your rate, or a fixed project fee
Itemized expenses (travel, software, subcontractors)
Any retainer applied or milestone reached
Tax, total and net payment terms (e.g. Net 14/30)

Getting paid as an independent consultant

The hard part of consultant invoicing usually isn’t the rate — it’s navigating how your client’s company actually pays. Small clients pay a person; enterprises pay a vendor, and a vendor has to fit their machinery: a valid purchase order (PO) number on the invoice, vendor onboarding, a W-9 or equivalent on file, and net-30 to net-60 terms enforced by an accounts-payable team that pays on its schedule, not yours. The consultants who get paid on time treat the invoice as a compliance document as much as a bill: they confirm the PO before delivering, put it on the invoice, and submit to the exact AP address in the exact format the client requires.

Structuring the invoice around your engagement

Match the invoice to how the engagement was sold, and reference the paperwork behind it:

Reference the signed proposal or statement of work (SOW) and the period or milestone billed
Include the client’s PO number prominently — many AP systems auto-reject invoices without one
For hourly work, attach a concise time summary by workstream; for project work, bill the named milestone on acceptance
Pass expenses through as a separate, itemized section with receipts, per your agreement
State clear payment terms and your accepted methods; for overseas clients, note currency and who covers transfer fees

Habits that shorten your payment cycle

Confirm the PO and the exact AP submission process before you start — chasing it after delivery adds weeks
Invoice the moment a milestone is accepted, not at month-end — every day of delay pushes the AP clock
Use net-15 with small clients; big companies will use whatever window you give them, so don’t hand them net-30 by default
Send a polite statement a few days before due date, and a firmer reminder the day it lapses
Keep invoice numbers and SOW references consistent so a client’s bookkeeper can match everything without emailing you

FAQ

How do consultants invoice clients?: List your hours or project fee with rates, add expenses if any, include your details and the client’s, set net terms, and send a PDF.
Do I need a PO number on a consultant invoice?: For enterprise and government clients, almost always — their accounts-payable systems match invoices to purchase orders and auto-reject anything without a valid PO. Get the PO number before you begin work and put it on every invoice for that engagement. Small clients usually don’t use POs, so a clear reference to your proposal is enough.
Should consultants bill hourly or by project?: Project or milestone fees are easier to sell to executives and reward you for efficiency; hourly protects you when scope is genuinely open-ended. Many consultants use a paid discovery phase to scope the work, then a fixed-fee proposal for delivery. Whichever you choose, the invoice should trace back to the agreed basis in the SOW.

More invoice templates

New to invoicing? Read how to make an invoice.