Invoice & estimate app for consultants

The invoice app for consultants

Consulting invoices go to accounts payable teams who need them exactly right — the PO number, the period, the hours, the expenses. Invoiceflint lets independent consultants send precise invoices from anywhere and follow up automatically when they sit unpaid.

Free to download for iPhone and Android · Pro free trial

Invoice

Hartwell Advisory

INV-2026-041

Bill to: Brightpath Logistics Ltd.

Example consulting invoice
Description	Qty	Rate	Amount
Strategy workshop facilitation (days)2 × $1,800.00	2	$1,800.00	$3,600.00
Advisory hours – October (hours)12 × $175.00	12	$175.00	$2,100.00
Market analysis report1 × $2,500.00	1	$2,500.00	$2,500.00
Travel expenses at cost – receipts attached1 × $386.20	1	$386.20	$386.20

Subtotal: $8,586.20
Total due: $8,586.20

PO #BP-77821. Services for October 1–31. Payment due Net 30.

Example consulting invoice made with Invoiceflint · Use it as a free template

What to include on a consulting invoice

A complete invoice gets approved and paid faster. Invoiceflint fills in the numbering, dates, and totals for you — here’s what else belongs on it.

1The client's purchase order (PO) number, if they use one.
2The billing period.
3Hours or days with a short description of the work.
4Fixed-fee deliverables as their own lines.
5Expenses at cost, with receipts attached.
6Payment terms that match your agreement — often Net 15 or Net 30.
7Your tax ID, if the client or your local tax rules require it.

How Invoiceflint helps consultants

Built for invoicing on the job, not at a desk.

Know when AP has opened it
See the moment the client views your invoice, so you know whether it reached the right person.
Automatic follow-ups on Net 30
Schedule reminders before and after the due date, so long payment terms don't become longer.
Attach expense receipts
Attach photos of receipts to the invoice so expenses are approved without back-and-forth.
Statements and reports
Export client statements and reports as CSV or PDF for your records and your accountant.

See every feature →

Billing tips for consultants

Always include the PO number

Larger clients can't pay an invoice without a matching purchase order. A missing PO is one of the most common reasons consulting invoices sit unpaid for weeks.

Send it to accounts payable, not just your contact

Your sponsor approves the work; accounts payable releases the money. Ask who should receive invoices at the start of the engagement.

Bill expenses separately and at cost

List travel and expenses on their own lines with receipts attached. It makes approval faster and keeps your fees clearly separate.

Invoicing questions from consultants

What should a consulting invoice include?

A consulting invoice should include the client's purchase order number if they use one, the billing period, hours or days worked with descriptions, any fixed-fee deliverables, expenses at cost with receipts, the total, payment terms, and your business and tax details.

How do consultants bill — hourly, daily, or by project?

All three are common. Hourly billing suits advisory work, day rates suit workshops and on-site engagements, and fixed project fees suit well-defined deliverables. Many consultants combine them on one invoice.

How do I invoice a monthly retainer?

Send an invoice at the start of each month for the agreed retainer, describing what it covers. If extra hours are billed beyond the retainer, add them as a separate line on the next invoice.

Why hasn't my consulting invoice been paid?

Common causes are a missing purchase order number, the invoice going to the wrong person, or the client's payment cycle. Confirm the invoice was opened, check it matches the PO, and send a polite reminder referencing the invoice number.

Related guides

Invoiceflint for other trades

Send your next consulting invoice from your phone.

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