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How to invoice as a freelancer: numbering, payment terms, late fees (with a free template)

Most freelance invoicing advice stops at "list what you did and add a total." The parts that actually decide whether you get paid on time are the boring ones: a numbering system you will not outgrow, payment terms the client agreed to before you started, and a late-fee line that means something. This guide covers those three, then gives you a template.

If you only need the field-by-field checklist, read how to write an invoice that gets paid first. This page assumes you know what goes on the page and focuses on the decisions around it: how you number invoices, when you send them, what you ask for, and what happens when a client is late.

1. Pick a numbering scheme once and never change it

An invoice number does three jobs. It lets the client's accounts team file and find the invoice. It lets you match a bank deposit to a specific job. And it tells anyone auditing your books later that no invoices are missing. All three break if numbers repeat, skip, or change format halfway through the year.

Three schemes that work for a solo freelancer:

Whichever you pick, the rules are the same: one number per document, never reused, never edited after sending. If you have to correct an invoice, do not overwrite it. Issue a credit note or a new invoice with the next number and a note that it replaces the old one. UK guidance lists a unique identification number as a required element of an invoice (GOV.UK, Invoicing and taking payment from customers), and the same expectation applies in practice almost everywhere.

Keep estimates and quotes on a separate sequence (EST-1001) so no client is ever sent two documents with the same number that mean different things. More on that in invoice vs estimate vs quote.

2. Payment terms: decide them before the work, not on the invoice

Payment terms are how long the client has to pay after the invoice date. The mistake freelancers make is choosing them at the moment of writing the invoice. By then the client has already formed an expectation, and "Net 14" on an invoice they thought was Net 30 reads as a surprise. Put the terms in your quote or contract, then repeat them on the invoice.

Which terms to use

• Due on receipt: small jobs, one-off work, and clients paying by card or transfer from their own account. Common for sums under a few hundred dollars.
• Net 14: a sensible default for freelancers. Long enough for a small business to process, short enough that it does not slide into next month.
• Net 30: larger companies with an accounts-payable department often cannot pay faster than this. Ask for it up front rather than pretending Net 14 will work.
• Deposit + balance: for anything over roughly a week of work. A 30 to 50 percent deposit invoice before you start, the balance on delivery. The deposit is not only cash flow; it is proof the client is real.
• Milestones: for projects longer than a month. Invoice at each agreed checkpoint so no single payment is big enough to hurt if it slips.

Whatever you choose, print a calendar date on the invoice. "Due 20 September 2026" leaves nothing to interpret. "Net 14" makes the client's bookkeeper count days, and they will not count them in your favour.

What the law says if you did not agree terms

Some places set a default. In the UK, if no payment date was agreed with a business customer, the customer must pay within 30 days of receiving the invoice or the goods or service (GOV.UK). In New York State, the Freelance Isn't Free Act requires a written contract for freelance work worth $800 or more and, where the contract does not specify a payment date, payment within 30 days of completing the work (New York State Department of Labor). Other states and countries have their own rules or none at all. These defaults are a safety net, not a strategy; agree terms in writing every time.

3. Late fees: the wording matters more than the number

A late fee does two things. It gives the client's finance team a reason to move your invoice up the pile, because a late fee creates a line item they have to explain. And it gives you something to point to when you chase. It rarely earns you much money, and that is fine.

Make it enforceable

A late fee the client never agreed to is a request, not a term. To make it stick, it has to appear in the quote or contract the client accepted, and then be repeated on the invoice. Three sentences are enough. The same wording, every document, every time.

How much you can charge depends on where you are. In the UK, business-to-business invoices carry a statutory right to interest at 8% above the Bank of England base rate plus a fixed debt-recovery amount, whether or not you wrote it on the invoice (GOV.UK, Late commercial payments). In the US there is no federal rule for business invoices; a flat percentage per month is common practice, but some states cap interest, so check your state's rules before you print a rate. When in doubt, a modest rate that you will actually enforce beats an aggressive one you will waive.

Wording you can copy

Payment is due by [date]. Invoices unpaid after the due date accrue a late fee of
[X]% per month (or part month) on the outstanding balance, as agreed in our quote
dated [date]. Work on further deliverables may pause until the balance is settled.

The last sentence is often more effective than the fee itself. Pausing work is a lever you control; collecting interest is a lever you may have to go to small-claims court for.

When the invoice is late anyway

1. Day after due: a one-line friendly reminder with the invoice attached again. Most late payments are lost emails, not refusals.
2. One week late: a second email, still polite, mentioning the late-fee clause and asking for a payment date.
3. Two weeks late: phone call or a message to your actual contact (not accounts payable). Ask what is blocking it.
4. Thirty days late: issue a statement showing the original invoice plus the accrued fee, and state your next step (pausing work, formal demand, or a claim).

4. The template

Below is a plain-text layout that covers every field the client's bookkeeper needs. Copy it into a document, or use the generator linked above, which lays out the same fields and does the arithmetic.

INVOICE                                        No. INV-1042
                                               Date: 6 Sep 2026
                                               Due:  20 Sep 2026 (Net 14)

From: [Your name / trading name]               To: [Client name]
      [Address]                                    [Client address]
      [Email] · [Phone]                            Attn: [Contact] · PO: [if any]
      [Tax / VAT number if registered]

Description                             Qty      Rate        Amount
--------------------------------------------------------------------
Homepage redesign, per quote EST-1017    1     $1,800.00   $1,800.00
Additional revision round               2       $150.00     $300.00
--------------------------------------------------------------------
                                              Subtotal      $2,100.00
                                              Discount         -$0.00
                                              Tax (0%)          $0.00
                                              TOTAL DUE     $2,100.00

Pay by bank transfer: [Account name · Account no. · Routing / sort code]
or by card: [payment link]

Terms: Payment due by 20 Sep 2026. Unpaid invoices accrue a late fee of
1.5% per month on the outstanding balance, as agreed in quote EST-1017.
Thank you for your business.

Replace the sample rate and fee with your own. The 1.5% figure is only an illustration of the layout; it is not a recommendation for your jurisdiction.

5. Three habits that make all of this automatic

• Invoice the same day you deliver. Every day between delivery and invoice is a day added to your payment terms that you did not agree to.
• Send to the payer and copy the contact. Ask for the accounts-payable address when you send the quote, so the invoice never sits in the wrong inbox.
• Keep every PDF. A dated folder of invoices is your income record. The IRS suggests keeping records that support your income for generally three years (IRS, How long should I keep records?). Save the file the moment you download it.

Frequently asked questions