How to budget for your sole trader tax bill throughout the year

Running your own business gives you freedom, but it also means your tax is not automatically taken from your income like it usually is through PAYE. That can make your Self Assessment bill feel heavier than it needs to, especially when 31 January comes around and you have other business costs to manage.

The good news is that your tax bill should not be a nasty surprise. With a simple routine, a separate savings pot and regular checks on your profit, you can plan for it throughout the year instead of dealing with panic at the deadline.

If you work with an accountant for sole trader, this becomes even easier because you can keep an eye on your likely tax position before the year ends, not after.

Start with your profit, not your turnover

A common mistake is budgeting for tax based only on what comes into your bank account. Your tax is based on profit, not turnover. That means you need to look at your income after allowable business expenses have been deducted.

For example, if you invoice £60,000 in the year but spend £15,000 on allowable business costs, your taxable business profit is closer to £45,000 before any personal tax adjustments. That gives you a much more realistic starting point.

This is why good bookkeeping matters. If your receipts, invoices and bank payments are not kept up to date, your profit figure becomes guesswork. A self-employed accountant can help you keep those numbers clear so you know what to set aside each month.

Understand what your sole trader tax bill may include

Your Self Assessment bill may include Income Tax and Class 4 National Insurance. Depending on your circumstances, it may also include payments on account towards the following year.

For the 2026/27 tax year, the standard Personal Allowance is £12,570. For taxpayers in England, Wales and Northern Ireland, the basic rate is 20%, the higher rate is 40% and the additional rate is 45%. If your self-employed profits are above £12,570, Class 4 National Insurance may also apply.

You do not need to memorise every rate, but you do need to know that your bill is not just a flat percentage of everything you earn. Your personal allowance, profit level, other income and payments already made can all affect the final figure.

That is where sole trader accountancy services can be useful. You get a clearer estimate earlier, rather than waiting until your return is due.

Set aside a percentage from every payment

One of the simplest habits is to move money into a separate tax savings account every time you get paid. This stops your tax money from being mixed with your everyday spending.

As a rough starting point, many sole traders put aside around 20% to 30% of profit. If your profits are higher, or you have payments on account, you may need to save more. The right percentage depends on your situation, so it is worth reviewing it properly instead of copying a general rule from someone else.

For example, if you earn £4,000 in a month and your allowable business expenses are £1,000, your profit is £3,000. If you set aside 25%, you would move £750 into your tax savings pot. Over time, this builds a cushion that makes January far less stressful.

Plan for payments on account

Payments on account catch many sole traders out. If your Self Assessment bill is more than £1,000 and you have not already paid most of your tax through PAYE or other deductions, HMRC may ask you to make advance payments towards the next year’s bill.

These payments are usually due on 31 January and 31 July. Each one is normally half of your previous year’s tax bill. So, if your tax bill was £4,000, HMRC may ask for £2,000 on 31 January and another £2,000 on 31 July towards the next year.

This is why your first large Self Assessment bill can feel painful. You may be paying the tax you owe for the previous year plus the first instalment towards the next one.

With proper sole trader accounting support, you can plan for this in advance and avoid being caught off guard.

Use bookkeeping software to stay current

If you only update your records once a year, budgeting for tax becomes much harder. You are always looking backwards. By the time you know your real profit, the money may already have been spent.

Using software such as QuickBooks can help you track income, expenses and profit more regularly. A certified QuickBooks accountant can also help you set up your categories properly, connect bank feeds and keep your records organised.

This does not mean you need to spend hours every week on admin. Even a simple monthly review can make a big difference. You can check what came in, what went out, what profit you made and whether your tax savings pot still looks sensible.

Review your budget every quarter

Your income may not be the same every month. Some sole traders have busy seasons, quiet periods, delayed invoices or one-off costs. That is why a fixed monthly tax saving figure can become inaccurate.

A quarterly review gives you a chance to adjust. If your profit has gone up, you can increase your tax savings before the gap becomes too large. If your profit has fallen, you can avoid locking away more money than you need.

This is also a good time to check whether you are claiming the right expenses, whether your pricing still works and whether your cash flow can handle upcoming costs.

A self-assessment tax return accountant can help you review your figures before the deadline, so your return is based on accurate records rather than rushed estimates.

Do not forget VAT if your turnover is growing

VAT is separate from Income Tax, but it can still affect your cash flow. In the UK, you must register for VAT if your taxable turnover goes over £90,000 in a rolling 12-month period.

This is important because the threshold is not based on your tax year alone. It looks at your taxable turnover over the last 12 months at any point. If your business is growing, you need to keep an eye on this regularly.

A VAT return accountant can help you understand when registration applies, how VAT affects your pricing and how to keep proper VAT records once you are registered.

Keep personal and business money separate

When personal and business spending are mixed, it becomes harder to know what you can safely spend. You may look at your bank balance and feel comfortable, without realising some of that money belongs to HMRC.

A separate business bank account makes life much easier. You can see your business income clearly, pay expenses from one place and transfer tax savings into a separate pot. It also makes bookkeeping cleaner and reduces the chance of missing allowable expenses.

This is one of the simplest steps you can take if you want your tax planning to feel less messy.

Budget for tax before you pay yourself

It is tempting to treat all remaining money as personal income once business costs are paid. A safer approach is to pay tax savings first, then pay yourself from what is left.

For example, your monthly routine could look like this:

1. Receive customer payments
2. Pay business expenses
3. Move your tax percentage into a savings pot
4. Set aside money for VAT or payroll if relevant
5. Pay yourself from the remaining balance

If you employ staff, you will also need to plan for wages, PAYE, National Insurance and pension duties. Payroll services for businesses in Slough can help you keep these employer responsibilities accurate and on time.

Get help before the bill becomes a problem

If you leave your tax planning until January, your options are limited. If you review your numbers during the year, you have time to adjust your savings, reduce unnecessary costs, chase invoices and plan your cash flow properly.

Professional accountants for self-employed individuals can help you understand what your numbers are telling you, not just file the return once the year has ended.

The aim is not to make tax complicated. It is to make it predictable. When you know roughly what is coming, you can run your business with more confidence.

Final thoughts

Budgeting for your sole trader tax bill is really about building better habits. Keep your records updated, review your profit regularly, save a sensible percentage from each payment and plan for the key HMRC deadlines.

You do not need a complicated system. You just need a clear one.

If you would like help keeping your books organised, estimating your tax bill and avoiding year-end surprises, Asmat & Co Accountants can support you with practical, fixed-fee sole trader accounting services. Get in touch today and let our team help you stay on top of your tax throughout the year.

FAQs

How much should I save for tax as a sole trader?

A common starting point is to save around 20% to 30% of your profit, but the right amount depends on your income level, expenses, other income and whether payments on account apply.

When do sole traders pay Self Assessment tax?

The main Self Assessment payment deadline is 31 January. If payments on account apply, you may also need to make a second payment by 31 July.

Do I pay tax on turnover or profit?

You pay tax on profit, not turnover. Your profit is your business income minus allowable business expenses.

What happens if I cannot pay my tax bill?

You should contact HMRC as soon as possible. You may be able to arrange a payment plan, but it is always better to act before the deadline passes.

Do I need an accountant to budget for my tax bill?

You are not legally required to have an accountant, but professional support can help you estimate your bill earlier, claim allowable expenses correctly and avoid last-minute stress.