If you are self-employed in Glasgow and you have been wondering how much of your income to set aside for your tax bill, you are not alone. It is one of the most frequently asked questions we hear from sole traders, freelancers, and newly self-employed people across the city — and it is a question worth getting right.

The short answer is between 25% and 30% of your profit. But to understand why, and to make sure that figure is right for your specific situation, it helps to understand how sole trader tax actually works in the UK.

How Is a Sole Trader Taxed in the UK?

As a sole trader, you pay two types of tax on your profits: Income Tax and Class 4 National Insurance Contributions. Both are calculated on your net profit — that is, your income minus your allowable expenses — not your turnover.

For the 2026/27 tax year, the rates are as follows:

• Personal allowance: £12,570 — no Income Tax below this threshold
• Basic rate Income Tax: 20% on profits between £12,570 and £50,270
• Higher rate Income Tax: 40% on profits between £50,270 and £125,140
• Class 4 National Insurance: 6% on profits between £12,570 and £50,270, then 2% above

So if your profit is £30,000 in 2026/27, your combined Income Tax and National Insurance bill is approximately £4,530. At £50,000 profit, the combined figure is around £9,930. Both figures assume self-employment is your only income source.

The 25% to 30% Rule — What It Actually Means

The most widely used rule of thumb for sole trader tax savings is to set aside 25% to 30% of your profit every time you are paid. This covers both Income Tax and Class 4 National Insurance for a basic-rate taxpayer.

If your profits are above £50,270 and some of your income crosses into the 40% higher-rate band, you should save closer to 40% to 45% of the portion above that threshold.

The practical approach that actually works:

• Open a dedicated savings account — one that exists only for your tax bill and is separate from your current account
• Every time you receive payment from a client, transfer 27% immediately into that account
• Treat that money as already spent — it was never yours, in the same way PAYE tax was never yours as an employee
• If you are earning above £50,270, increase the percentage on the portion above that level

The key principle is consistency. Setting aside a percentage every single time removes the discipline problem of trying to save a large lump sum in December or January.

Payments on Account — The Detail That Catches Every New Sole Trader

This is the single detail that surprises almost every sole trader in their first year of self-employment, and it is responsible for a significant amount of the financial stress we see from clients who manage their own accounts.

HMRC does not just ask you to pay your tax bill once. If your annual tax liability exceeds £1,000, you are required to make payments on account — which means paying your current year’s bill plus 50% of next year’s estimated bill, all in January.

Here is what that looks like in practice. If your first year’s combined tax and National Insurance bill is £4,000, HMRC will ask you for £6,000 in January — £4,000 for the year just gone and £2,000 as an advance payment toward the year ahead. By July 31st, a further £2,000 is due.

This is the most common source of financial shock for self-employed people in Glasgow who manage their own accounts without professional support. If you did not know about payments on account and your January bill arrives as a 50% larger figure than expected, that is why.

The solution: save slightly more than the standard 25% to 30% in your first two years to build a buffer against the payments on account. And get your January bill calculated in advance — not in January — so the number is never a surprise.

Why Your Allowable Expenses Directly Reduce Your Tax Bill

Your sole trader tax bill is calculated on your net profit, not your gross income. Every pound of allowable expenses you claim legitimately reduces your profit, which in turn reduces both your Income Tax and your Class 4 National Insurance.

Common allowable expenses that sole traders in Glasgow can claim include:

• Business mileage at HMRC-approved rates — 45 pence per mile for the first 10,000 miles in 2026/27
• Home working costs — either the flat rate of £6 per week or a calculated proportion of actual household bills
• Equipment purchased for the business — laptops, tools, cameras, and other assets used in your work
• Professional subscriptions and training directly related to your trade or profession
• Accountancy and professional services fees
• Phone and broadband — the business proportion, not personal use
• Software subscriptions used for work purposes
• Marketing and advertising costs, including social media advertising

Many sole traders in Glasgow are not claiming everything they are entitled to. One of the most common outcomes of a first conversation with a new client is identifying expense categories they have been missing for months or years. Reviewing your allowable expenses properly often reduces your tax bill by more than the cost of the accountancy service itself.

Find out how 1341 Accountancy helps sole traders in Glasgow claim every expense they are entitled to — visit our Sole Trader Accounting page.

Making Tax Digital and Your Tax Savings Habits

From April 2026, sole traders and landlords with qualifying gross income over £50,000 are required to use Making Tax Digital for Income Tax — submitting quarterly digital updates to HMRC through approved accounting software rather than a single annual Self Assessment return. The threshold drops to £30,000 from April 2027.

This change has an unexpected benefit for tax savings: when you review your income and expenses four times a year instead of once, you maintain a much clearer picture of your likely tax bill throughout the year. The quarterly rhythm naturally aligns with setting aside the right percentage each month.

If you are approaching the £50,000 income threshold, getting the right software and systems in place now is significantly easier than doing it in a rush when compliance becomes mandatory.

Learn how 1341 Accountancy helps sole traders get set up for Making Tax Digital — visit our Making Tax Digital page

A Simple Monthly System for Glasgow Sole Traders

Here is the approach we recommend to every sole trader we work with:

• Step 1: Open a dedicated savings account used only for your tax money
• Step 2: Transfer 27% to 30% of every invoice payment immediately — before you spend anything else
• Step 3: Keep your bookkeeping up to date each month — even 20 minutes a month is enough for a simple sole trader
• Step 4: Get your accountant to calculate your estimated January bill in October or November — not January
• Step 5: Pay the bill in January, leave the July payment on account in the savings account, and reset for the new year

This removes the January panic entirely. When your bill arrives you already have the money, you already know the figure, and the only thing left to do is submit and pay.

When Should You Speak to an Accountant About Your Tax Savings?

The honest answer is as early as possible. The earlier you establish the right savings habits and
understand your specific tax position, the less you pay in mistakes, penalties, and missed deductions
further down the line.

Key moments where professional support makes the biggest difference:

• In your first year of self-employment — before the payments on account structure surprises you
• When your income grows past £30,000 profit — where the tax saving from proper planning becomes significant
• When you approach the £50,000 threshold that triggers Making Tax Digital
• When you start considering whether a limited company structure might save you more tax

Book a free 30-minute consultation with Laura and Emma at 1341 Accountancy — clear, jargon-free advice for sole traders in Glasgow.