How to Invoice as a Freelancer: Hourly, Fixed and Retainer

How do you invoice as a freelancer?

Agree the billing model before the work starts, then turn it into invoice lines the client can check: hours times rate from a timesheet, a milestone percentage of a fixed fee, or a monthly retainer plus any overage. Add expenses as separate lines, quote the client’s PO and tax details, and invoice on a fixed rhythm.

The mechanics of a single invoice (what goes in each box, numbering, sending) are the same for everyone and are covered in how to write an invoice. This guide is about the parts that are specific to freelancing: how each way of charging becomes a line on the page, how deposits and expenses fit in, what changes when the client is abroad, and how often to bill so your cash keeps pace with your work.

Which billing model should the invoice follow?

Every freelance invoice is a record of one agreement: the way you and the client decided to price the work. Most freelance and consulting work fits one of six models. They differ in who carries the risk of the job taking longer than expected, and that is exactly what the invoice lines reveal.

Notice that the description column does most of the work. A client’s accounts team matches an invoice against something: a proposal, a purchase order, an approved timesheet. Name that thing in the description (“as per proposal v2”, “timesheet attached”, “milestone 2 of 3”) and the invoice is approved without anyone needing to email you. If you have not settled on a rate yet, the freelance rate calculator works backwards from the income you need, and how to set freelance rates covers choosing between these models in more depth.

How to invoice for hourly work

Hourly invoicing starts with a timesheet, not the invoice. Record start and stop times, or durations, per task and per day, with a few words on what you did. The invoice then carries either one line per task, one line per day, or a single line for the period with the timesheet attached. For most clients, a single line plus an attached timesheet keeps the invoice short and the detail auditable.

The decision people skip is the billing increment. Many freelancers and consultants bill in 6-minute units (tenths of an hour) or 15-minute units, rounding each entry up. That is a legitimate convention, but it must be agreed in the contract, and the choice changes the invoice more than most people expect. Say a designer bills $85 an hour and logs this week:

The same 522 minutes of work produce invoices $85 apart. Rounding each entry up to 15 minutes adds 0.8 hours, or $68.00, which is 9.2% more than the exact figure. Rounding up to 6 minutes adds $17.00, or 2.3%. Rounding to the nearest 15 minutes happens to cut this week’s invoice by $17.00, and on another week it would add to it.

The fair, defensible approach is simple: state the increment and whether you round each entry or the total in your contract, then apply it every time. Clients rarely object to 6-minute billing when they know about it in advance. They do object when a timesheet full of 15-minute blocks arrives with no warning.

Invoicing a day rate

A day rate is hourly billing with a bigger unit, and it raises the same question: what counts as a unit. Say a contractor charges £450 a day, and the contract defines a day as 7.5 hours with half days billed at 50%. A week of three full days and one morning is 3.5 days, so the invoice line is 3.5 days at £450.00, or £1,575.00. The hourly equivalent is £60, which is worth knowing when comparing offers; the hourly to salary calculator scales it to a year.

What the day rate does not settle on its own is the long day. If one of those days ran to 9.5 hours, a day-rate contract with no overtime clause still bills it as one day. If the client regularly needs more than the defined day, add an overtime rule in writing (for example, hours beyond 7.5 billed at £60 each) before it happens, not on the invoice after it has.

Fixed-fee projects billed by milestone

A fixed fee sent as one invoice at the end means you finance the whole project yourself, and you carry the risk that the client disappears before paying. Splitting the fee into milestones fixes both problems. A common split is 30/40/30: a deposit on signing, a middle payment at a clear approval point, and the balance on delivery.

Say a web developer agrees a $12,000 fixed fee for a website. The stages, each with its own invoice, look like this:

Tie each trigger to an event both sides can see, such as a signed approval or a handover, never to a vague phrase like “when the design is mostly done”. If a milestone is blocked by the client (feedback that never arrives), a clause that lets you invoice the stage after a set number of days of waiting keeps the project from stalling your income. Deposits and stage payments are covered alongside other payment terms in the payment terms guide. When each stage payment arrives, a numbered receipt from the receipt maker records it against the project.

Two ways of presenting the final invoice are common. The first lists only the 30% stage. The second lists the whole project fee and deducts what has already been paid, which gives the client the full picture on one page:

The change request is the reason fixed-fee freelancers stay profitable. Anything outside the written scope gets its own quote, its own approval and its own line, priced before you do it. The estimate and quote generator handles that quote, with a valid-until date and a sign-to-accept block, and converts it into an invoice once approved; how to write an estimate covers pricing the work itself. If the difference between a quote and an invoice is fuzzy for a client, invoice vs receipt vs quote sets out which document does what. In the invoice generator, the deduction goes in the “amount already paid” field, which turns the total into a balance due.

How to bill a retainer

A retainer is a monthly fee for a reserved block of your time or a defined set of work. It is usually billed in advance, at the start of the month it covers, because the client is paying for your availability. Anything above the block is billed in arrears, on the next invoice, once the hours are known.

Say a copywriter agrees a $2,400 monthly retainer covering up to 20 hours, which is an effective $120 an hour, with extra hours at $135. In September the client used 26.5 hours. The invoice issued on 1 October carries both the new month and last month’s overage:

Pricing overage above the effective retainer rate ($135 against $120) is deliberate: the retainer rewards the client for committing, and ad hoc hours cost more because you had to find room for them. Show the hours used every month even when there is no overage, so the client sees what the retainer buys and you have a record if they later ask to cut it.

• Unused hours: decide in the contract whether they expire at month end, roll over for one month only, or roll over up to a cap. Unlimited rollover quietly turns a retainer into a prepaid bank of hours that can all land in one month.
• Notice period: a retainer should say how much notice either side gives to end it, typically one billing period, so the last invoice is not a surprise.
• Scope retainers: if the retainer covers deliverables (four articles a month) rather than hours, list the deliverables on the invoice and say how extra ones are priced.

The invoice generator does not create recurring invoices on a schedule. It does keep a history of saved invoices and clients in your browser, so each month you reload the client, update the month and hours, and the suggested invoice number continues your series.

Expenses and reimbursables

Expenses you pay on a client’s behalf, such as stock images, hosting, printing or travel, go on the invoice as separate lines, never folded into your fee. There are two ways to charge them, and the contract should say which one you use.

• Pass-through: the client pays exactly what you paid. You attach or keep the receipt, and the line amount equals the receipt.
• Marked up: you add a handling percentage to cover the time spent sourcing, paying and chasing, and the cost of carrying the money until the client pays. It must be agreed in advance and should be visible, not buried.

A 10% markup is a 9.09% margin on the recharged amount, because the markup is measured against your cost and the margin against the client’s price. The markup calculator converts between the two. Whether a markup is appropriate is partly a relationship question: many clients accept one on sourced materials and object to one on travel.

Receipts matter on both sides of the invoice. The IRS says supporting documents for business expenses should show the payee, the amount paid, proof of payment, the date incurred and a description showing the amount was for a business expense (https://www.irs.gov/businesses/small-businesses-self-employed/what-kind-of-records-should-i-keep). Keep the receipt even when the client reimburses you: it supports your own books, and freelance tax write-offs explains how costs you are not reimbursed for can still reduce your tax.

That last condition means a marked-up cost cannot be a disbursement for UK VAT, because the exact amount is not being passed on. Outside the UK the rules for reimbursed expenses differ by country, so check with your own tax authority rather than assuming the UK treatment applies. In the invoice generator, each line has its own Taxable tick, which is how you leave a genuine disbursement out of the tax while taxing your fee.

How to invoice a client for the first time

The first invoice to a new client is the one most likely to be delayed, and usually not because of anything on the invoice. Larger clients pay through an accounts payable process that needs you set up as a supplier first, and an invoice that arrives before that is done can sit unprocessed. Ask these questions when the contract is signed, not when the invoice is due.

The Form W-9 point is worth understanding if you work with US clients: the IRS describes it as the form used to give your correct taxpayer identification number to a person who is required to file an information return reporting income paid to you (https://www.irs.gov/forms-pubs/about-form-w-9). Which form, if any, applies to you depends on your status and residence, so answer the client’s request with your own adviser if you are unsure.

Your own details matter as much as theirs. In the UK, a sole trader must show their name and any business name used, plus an address where legal documents can be delivered if trading under a business name, and a limited company must show its full name as it appears on its certificate of incorporation (https://www.gov.uk/invoicing-and-taking-payment-from-customers/invoices-what-they-must-include). Put your payment details, including the exact account name, on the invoice itself so nobody has to reply asking for them.

Invoicing international clients

Working for a client in another country raises two separate questions, and it helps to keep them apart. The first is commercial: which currency the invoice is in, and who absorbs exchange-rate movements. The second is tax: whether VAT or a similar tax belongs on the invoice at all, and whose job it is to account for it.

Choosing the invoice currency

Whichever currency the invoice is written in, one side of the deal carries the exchange-rate risk between the invoice date and the payment date. Say a UK-based consultant invoices a US client $5,000 on Net 30 terms, when the rate is a hypothetical 1 GBP = 1.27 USD. At that rate the invoice is worth £3,937.01. What arrives depends on the rate on the day the client pays.

Invoicing in the client’s currency makes you easier to buy from and puts the risk on you: a 4.7% move in the rate cost this consultant £177.61, or 4.51% of the expected fee. Invoicing in your own currency puts the risk on the client, which some clients will accept and others will refuse, particularly where their systems only pay in one currency. Neither is wrong. What matters is choosing deliberately.

• Short payment terms shrink the window in which the rate can move. A deposit taken in advance removes that share of the risk entirely.
• For long projects in a foreign currency, some freelancers add a clause that re-prices future stages if the rate moves beyond an agreed band.
• Conversion fees are a separate cost from rate movement. Find out what your bank or payment provider charges to receive and convert foreign currency before setting the price.
• If you are VAT registered, your tax authority may require certain amounts in your own currency. For UK VAT invoices, HMRC allows the amount payable excluding VAT in any currency but requires the total VAT chargeable to be expressed in sterling (VAT Notice 700/21, section 4.1).

Cross-border VAT and the reverse charge, in general terms

For services, the starting point in both the EU and the UK depends on who the customer is. When a business supplies services to another business, the general rule is that the supply is taxed where the customer is established or belongs. When the customer is a private consumer, the general rule is that it is taxed where the supplier is established (EU VAT Directive articles 44 and 45; HMRC VAT Notice 741A, sections 6.2 and 6.3). Both regimes list many exceptions, including services connected with land, events and certain services to consumers abroad.

When a business-to-business service is taxed in the customer’s country and the supplier is not established there, the EU rule is that the customer, not the supplier, is liable for the VAT. That is the reverse charge. The invoice then shows the customer’s VAT identification number and the words “reverse charge”, and the supplier does not add their own VAT (European Commission, invoicing rules and article 196). The general effect in each common situation is summarised below.

One practical step applies everywhere in the EU: check a client’s VAT number before you rely on it. The European Commission explains that an EU VAT number generally begins with the country code followed by digits or characters, and that its validity can be checked in the VAT Information Exchange System (VIES). If you need to calculate the VAT on a domestic invoice, the VAT calculator handles both adding VAT and extracting it from a gross price, and GST and sales tax compliance covers registration thresholds and filing.

In the invoice generator, the client block has a tax ID field for the customer’s VAT number, the reverse charge wording goes in the notes, and unticking Taxable on each line keeps your own VAT off it. It supports 48 currencies with the correct number of decimal places, but it does not support Arabic, Urdu, Hindi, Chinese, Japanese or Korean scripts or right-to-left text, so client names in those scripts need to be written in Latin letters.

How often should a freelancer invoice?

Invoicing cadence is the single biggest lever on a freelancer’s cash flow, and it costs nothing to change. The payment terms decide how long a client has to pay an invoice. The cadence decides how long the work sits before an invoice even exists.

Say a freelancer takes a three-month project from January to March, worth $9,000, and compares three ways of billing it. Option A is one invoice on completion at Net 30. Option B is $3,000 billed at the end of each month at Net 30. Option C is 30/40/30: a $2,700 deposit due on receipt in January, $3,600 at design sign-off in mid-February on Net 14, and $2,700 on completion at Net 14.

All three clients pay on time and every approach collects $9,000 by the end of April. The difference is how much of your work you are lending to the client along the way, and how much you lose if they stop paying. With option A, a client who goes quiet in April leaves you unpaid for three months of work; with option C, the exposure is the final 30%.

• Invoice the same day a milestone is reached or a period ends. A week’s delay in sending is a week added to every payment.
• Hourly and retainer work: monthly is the usual floor. Weekly or fortnightly suits new clients, heavy months, or anyone with thin cash reserves.
• Align with the client’s payment runs if you know them. An invoice that just misses a monthly run can wait weeks longer than its terms suggest.
• Track it. The days sales outstanding calculator shows how many days of sales are tied up in unpaid invoices, and the cash flow forecast template turns expected payment dates into a runway.

Freelancer invoicing mistakes that cost money

Most freelance payment problems trace back to something decided, or not decided, before the invoice was written. These are the ones specific to working alone.

• Starting work without a written agreement on the billing model, the rounding rule, the expense policy and the payment terms. The invoice cannot fix what the contract left open.
• Letting scope creep go unbilled. Small extras add up; each one deserves a change request, even if you decide to waive it (show it as a line at zero so the client sees the value).
• Vague descriptions like “Services rendered”. A client cannot approve what it cannot match to an agreement, and neither can you, a year later, when a dispute arises.
• Quoting a foreign client before deciding the currency and checking the tax treatment. Both change what you actually receive.
• Editing an issued invoice instead of correcting it properly. Once an invoice is sent, fix mistakes with a credit note or a new invoice rather than overwriting the old one, so your records stay consistent.
• Treating every invoice as a one-off. Freelance income is lumpy; a regular invoicing day each week or month is what keeps it predictable.

If an invoice is already late despite all this, how to follow up an overdue invoice covers reminder timing, late fees and statutory interest, and escalation.

Sources

• Place of taxation for services, business-to-business (article 44) and business-to-consumer (article 45) general rules and the list of exceptions, European Commission: https://taxation-customs.ec.europa.eu/taxation/vat/vat-directive/place-taxation_en
• Reverse charge: the customer is liable for VAT on certain services from a supplier not established in the customer’s country (article 196), European Commission: https://taxation-customs.ec.europa.eu/taxation/vat/vat-directive/persons-liable-vat_en
• EU invoice content, including the customer’s VAT number when the customer is liable and the words “reverse charge”, European Commission: https://taxation-customs.ec.europa.eu/taxation/vat/vat-businesses/invoicing_en
• EU VAT identification number format and checking validity in VIES, European Commission: https://taxation-customs.ec.europa.eu/taxation/vat/vat-directive/vat-identification-numbers_en
• UK place of supply of services: B2B and B2C general rules, commercial evidence for customers outside the UK, and the reverse charge for UK recipients (VAT Notice 741A, sections 5.1, 6.2, 6.3), HMRC: https://www.gov.uk/guidance/vat-place-of-supply-of-services-notice-741a
• UK VAT invoices: VAT total in sterling with other amounts in any currency (section 4.1), HMRC VAT Notice 700/21: https://www.gov.uk/guidance/record-keeping-for-vat-notice-70021
• UK disbursements versus recharges, the eight conditions and the consultant travel example, HMRC: https://www.gov.uk/guidance/vat-costs-or-disbursements-passed-to-customers
• What a UK invoice must include, and extra details for sole traders and limited companies, GOV.UK: https://www.gov.uk/invoicing-and-taking-payment-from-customers/invoices-what-they-must-include
• What supporting documents for business expenses should show, IRS: https://www.irs.gov/businesses/small-businesses-self-employed/what-kind-of-records-should-i-keep
• Purpose of Form W-9, IRS: https://www.irs.gov/forms-pubs/about-form-w-9

Where to go next

If you are writing your very first invoice, how to write an invoice walks through every field in order. To decide how long clients get to pay and how deposits are worded, read invoice payment terms explained.

When a client needs a pro forma invoice before paying a deposit, or asks for a receipt afterwards, invoice vs receipt vs quote explains each document. And if a payment is overdue, chasing an unpaid invoice sets out the steps from a polite reminder to a claim.

Common questions