The complete UK freelancer's guide to contracts, invoicing & tax

Going freelance can feel daunting at the start. It needn't be. You're good at the work — that's rather the point — but nobody hands you the business side, and at first it can look like a wall of admin and unfamiliar phrases: Self Assessment, payments on account, statutory interest.

This guide walks through what actually needs doing in your first years, roughly in the order you'll meet it, so you can take it a step at a time. Most of it is more straightforward than it first appears, and where a step means dealing with HMRC directly we'll point you to the official page rather than paraphrase it.

A quick note before we start: TrustSolo isn't a law firm or an accountancy, and nothing here is legal or financial advice. It's a plain-English guide to help you get set up sensibly. For anything high-value or out of the ordinary, it's worth getting professional advice.

Treat it as a business from day one

The moment someone pays you for your work, you're running a business — even if it's just you at the kitchen table. Two small habits, started now, save a good deal of bother later.

The first is to keep your money separate. As a sole trader you're not legally required to have a business bank account, but keeping your freelance money in an account of its own makes your income obvious at a glance and takes the guesswork out of tax time. One thing worth knowing: many banks don't permit business use on a personal account, so the tidy route is a dedicated business account — plenty are free and quick to open.

The second is to keep records from your very first invoice. HMRC requires you to keep records of your business income and expenses, and to hold onto them for at least five years after the 31 January submission deadline for the relevant tax year. That sounds heavier than it is, so long as you capture things as they happen rather than in a year-end scramble. You can keep records by hand in a spreadsheet, though it's one more thing to stay on top of; the easier version is to let them fall out of the work you're already doing — TrustSolo, for one, keeps the record as you invoice and feeds it straight into your tax estimate. Either way, the scramble to avoid is reconstructing a year's figures the week before a deadline.

You don't need an accountant on day one. You do need somewhere tidy to note what you earned and what you spent.

Get set up with HMRC

Most people going freelance start as a sole trader — it's the simplest way to work for yourself, and you can always change structure later if you need to.

You have to register for Self Assessment once you earn more than £1,000 from self-employment in a tax year (the tax year runs 6 April to 5 April). That £1,000 is the trading allowance: below it, you generally don't need to tell HMRC at all; above it, you do. The deadline is to register by 5 October in the tax year after the one you started — so there's usually a comfortable window, but it's not one to forget.

Registering is a short online form. It doesn't trigger a bill; it simply puts you in the system and gets you a Unique Taxpayer Reference (your UTR), which you'll need when it's time to file. Do it once you're past the threshold and it's off your list. If you'd like the process step by step — the form, your UTR, the dates — see our guide to registering as self-employed with HMRC.

Price yourself to survive, and to grow

The most common early mistake is pricing off a salary. If you'd have earned £35,000 employed, £35,000 of freelance income does not leave you in the same place — because your rate now has to cover the things an employer used to: tax and National Insurance, holidays, sick days, a pension, your software and equipment, and all the unpaid hours spent finding work and doing admin.

So work backwards from the income you actually need, not from a job title. As a rough shape: decide what you want to take home, add tax and your costs, then divide by the number of days you can realistically bill — which is never all of them. Our free rate calculator does this for you and needs no sign-up, and our UK freelancer rates report shows what people across nine disciplines actually charge.

On structure, a day rate is simple and keeps you covered if a job grows; a fixed project price rewards you for working efficiently but means you carry the risk if it overruns. Many people start on day rates and move towards project or value pricing as they get a feel for how long things really take.

Whatever you land on, try not to undercharge to win the first few jobs. An opening rate sets an anchor that's surprisingly hard to move later. Start at a number you can say out loud without wincing — you can always raise it as you go.

Always work under a written agreement

A written agreement isn't about expecting the worst of a client. It's about both of you having the same understanding of what was agreed, for the moments when memories differ. The essentials are modest: the scope of the work, the price, the payment terms, rough timings, and what happens if the work changes or the client pulls out partway through.

Most freelance disputes come from something left unspoken — "I assumed that was included." A clear agreement, sent before the work starts, quietly heads off the great majority of them. It needn't be twenty pages; a clean one-pager covering the essentials beats a friendly handshake every time. If you're not sure you legally need a written contract, or what a good one should say, our guide to the six clauses every freelance contract needs goes further.

This is one area TrustSolo is built to help with. Its contract templates are customisable starting points, structured around common UK freelance practice and organised by discipline — they set out clear terms on the things that matter, and leave the commercial decisions to you. They're starting points rather than legal advice, and for a high-value or unusual engagement it's worth getting a professional opinion. You can see how they work under contracts.

Invoice properly, and get paid on time

A good invoice is clear and leaves nothing to interpret. For a sole trader who isn't VAT-registered, it should show a set of standard details: a unique invoice number, your name and any trading name, your address and contact details, the client's name and address, a clear description of the work, the date, and the amounts with a total — our guide to how to invoice as a freelancer walks through each one. (If you register for VAT later, you'll need to issue a fuller VAT invoice.)

Set the payment terms up front and put the due date on the invoice — 14 or 30 days is typical — then send it promptly, because the clock only starts when the client receives it.

When a payment does run late, a calm, factual reminder usually settles it. If it genuinely drags on and the client is a business, the law is on your side: you have a statutory right to charge interest of 8% plus the Bank of England base rate, along with a fixed sum towards your recovery costs (£40, £70 or £100 depending on the size of the debt). And where no payment date was agreed, a business payment counts as late 30 days after you invoiced or delivered the work. You'll rarely need to invoke any of this, but it's reassuring to know it's there — and our guide to late-paying clients sets out the full escalation ladder if you ever do.

In practice, most clients aren't trying to avoid paying — they're busy, and an invoice has slipped down the pile. A prompt, clear invoice with a due date on it prevents most late payment before it happens. TrustSolo handles the invoicing and the payment link so this part mostly takes care of itself.

Stay on top of tax and National Insurance

This tends to be the part people dread most. In practice it's mostly a matter of setting a little aside as you go, so the bill isn't a surprise.

Here's the shape of it. You pay Income Tax on your profits — that's your income minus allowable business expenses, not your total earnings — plus Class 4 National Insurance, which is a percentage of your profits above a threshold. There's a bit of good news on the other National Insurance band: most self-employed people no longer pay Class 2 at all — above the small-profits threshold it's now treated as paid, so your record still counts. (The exact rates and thresholds change each year, so it's worth glancing at the current figures on that page.) Our guide to how much tax you'll pay works through it with examples.

You declare all of this once a year through Self Assessment. You file online and pay by 31 January, for the tax year that ended the previous 5 April; if you file on paper the deadline is 31 October.

One thing worth knowing early, because it catches people out: payments on account. Once your tax bill passes £1,000, HMRC asks you to pay towards next year's bill in advance, in two instalments on 31 January and 31 July, each roughly half of last year's bill. The first time this happens it effectively lands alongside your actual bill, so the January total can be larger than expected. It's not an extra charge — it's paid forward — but it's much easier if you're expecting it. We explain it in full in payments on account, explained.

Making Tax Digital for Income Tax is the other date to know, and for some freelancers it has already arrived. It's being phased in by qualifying income: over £50,000 since 6 April 2026, over £30,000 from 6 April 2027, over £20,000 from 6 April 2028. It means keeping digital records and sending HMRC quarterly updates.

So if your qualifying income is over £50,000, this isn't something on the horizon — you're in it now. HMRC decides using your last completed return, so whether you're brought in from April 2027 turns on your 2025–26 figures. Below £20,000 you're not required to use it yet and carry on with Self Assessment as before. Our guide to MTD for Income Tax covers exactly who's affected, when, and what "qualifying income" counts.

TrustSolo keeps a running estimate of your Income Tax and Class 4 NI as you invoice, so you can see roughly what's building up. It's a guide to what's likely owed — not your tax return, and it doesn't file anything to HMRC for you. For anything complicated, an accountant is money well spent. You can see the estimate under tax.

A rule of thumb worth adopting on day one: move around 25–30% of everything you invoice into a separate pot the moment it lands. It won't be exact — your real bill comes out of Self Assessment — but it means the money is already there when the deadline arrives, instead of having to be found.

Look at whether you need insurance

Depending on the work you do, some cover is worth a look. Professional indemnity insurance matters if a client could claim your advice or work caused them a loss; public liability matters more if you work on client premises or meet people in person. Some clients will ask you to hold cover as a condition of the contract.

Not everyone needs every policy, and this isn't a reason to panic. It's worth ten quiet minutes to check what's normal in your field, and then it's decided.

Build a pipeline and a small cushion

For most freelancers the real challenge isn't the admin — it's the feast and famine. The fix is unglamorous but it works: keep a little marketing ticking over even when you're busy, so there's a next client on the horizon before you actually need one.

Try, too, not to rest everything on a single client. If one client is most of your income and they cut back, that's a hard month. A spread of two or three is steadier.

And build a cushion when you can. Over time, a small buffer for the quiet stretches — and for the tax bill — turns a slow month from a crisis into a mild inconvenience. This grows slowly, and that's fine; the point is the direction, not having it all in place by the end of month two.

Settle into a simple rhythm

None of this is hard to do once. What wobbles is keeping on top of it. A light routine is what holds everything together:

• Log income and expenses as they happen, or once a week — not in a January panic.
• Send invoices promptly, and keep an eye on what's still outstanding.
• Move your tax set-aside across the day money lands.
• Keep the dates that matter somewhere you'll actually see them: 31 January and 31 July for tax, and if you're newly self-employed, 5 October to register and 31 October for paper returns.

This is where TrustSolo is meant to earn its place: it takes the friction out of the contract-to-invoice-to-paid loop and keeps that tax estimate running alongside, so the day-to-day mostly looks after itself. It won't file your return or stand in for advice when you need it — it's there so the small stuff doesn't pile up into a big thing.

You really don't have to get all of this right at once. Register when you cross the threshold, put a written agreement in place before the work starts, invoice promptly, set money aside as you go, and keep tidy records. Do those five and most of the rest tends to follow.

When you're ready to put the paperwork on autopilot, you can start free — no card required.