The basics
- your name or business name, address and email
- the client’s company name and address
- an invoice number, the invoice date and a due date written as a date
- the client’s purchase order (PO) number and the name of the person who approved the work
- hours or days at your rate, or the fixed fee, line by line
- expenses you pass on, such as stock photos or font licenses, on their own lines
Many accounts teams will not pay an invoice without a PO number and an approver’s name, so ask for both when the work is agreed.
When US clients have to pay you
Three states give freelancers a written contract and a payment deadline. The client has to provide the contract, and if it sets no payment date, payment is due within 30 days of finishing the work.
- New York State: work of $800 or more, counting contracts with the same client over the previous 120 days (Freelance Isn’t Free Act).
- California: work worth more than $250, counted over four months (Freelance Worker Protection Act, in force since 2025).
- Illinois: work of $500 or more in a 120-day period, for contracts that took effect after July 1, 2024. Construction services are not covered.
Put the agreed due date on every invoice anyway, so the 30-day default never has to be argued.
Sources: New York Attorney General, NY Department of Labor, California Governor's office, California Senate, Illinois Department of Labor
Deposits, milestones and kill fees
On a fixed-fee project, invoice a deposit or the first milestone before you start, and agree a kill fee for work the client cancels part way through. Bill each later milestone against the same project name and say which one it is, for example “milestone 2 of 3”, so the client can see what is paid and what is left.
Who owns the work
Say on the invoice what rights the client gets and when they pass, for example “license to use on web and social, effective on payment in full”.
In the US you keep the copyright in what you create unless it is a work made for hire, which for a freelancer needs one of nine listed kinds of work and a written agreement signed by both of you. A transfer of copyright is valid only in a writing signed by the owner, so an invoice grants a license; it does not hand over the copyright by itself.
In the UK the author of a work is the first owner of its copyright, unless an employee made it in the course of their job.
Sources: U.S. Copyright Office Circular 30, 17 U.S.C. 204, Copyright, Designs and Patents Act 1988 s.11
Billing a US business: W-9 and 1099-NEC
A business that pays you $2,000 or more in a year, for payments made after December 31, 2025, files a Form 1099-NEC, and it will ask for your Form W-9 first. Payments to corporations are generally not reported. If you do not give a correct taxpayer ID, the client must hold back 24% of each payment as backup withholding, so send your W-9 with the first invoice.
Sources: IRS: Form 1099-NEC, IRS: 1099-NEC instructions, IRS: Form W-9, IRS: backup withholding
Freelancing in the UK
A UK invoice needs a unique number, your name and any business name you trade under, your address, the client’s name and address, a description of the work, the date the work was done, the invoice date and the total. Charge VAT only once you are registered: registration is compulsory when your taxable turnover for the last 12 months goes over £90,000.
If a business client pays late, the law lets you add interest at 8% over Bank Rate plus a fixed £40, £70 or £100, depending on the size of the debt. Work it out with the late payment interest calculator, or use the UK invoice template for a UK-only layout.
Sources: gov.uk: what an invoice must include, gov.uk: register for VAT, gov.uk: charging interest, gov.uk: debt recovery costs
Rules checked against the official sources linked above on October 19, 2026. Example prices are illustrative. This is general guidance, not legal or tax advice.