If you run two separate businesses as a sole trader, you do not combine them into one set of figures on your self assessment. HMRC requires you to report each trade on its own separate schedule. This is the box-by-box guide to getting it right.

Most self assessment tax return guides assume you have one trade. They walk you through the SA103S (short) or SA103F (full) pages once and move on. That misses the critical detail for anyone running, say, a Bristol-based landscaping business alongside a separate ecommerce store, or a Manchester freelance consultancy with a buy-to-let portfolio that has crossed into trading.

This guide covers the specific forms, the box numbers, the expense allocation traps, and what happens when one trade makes a loss while the other turns a profit. As ICAEW qualified accountants, we handle these scenarios regularly for UK business owners across every sector.

When Do You Have Multiple Trades, Not One Business?

HMRC looks at whether each activity is a separate trade. The test is not whether you invoice from the same bank account or use the same laptop. It is whether the activities are distinct in fact.

You likely have multiple trades if:

  • You run a building contracting business in Sheffield and also sell handmade furniture online from your workshop. Different customers, different skills, different supply chains.
  • You operate a cleaning company in Birmingham and a separate dog-walking service. Different services, different pricing models, different client bases.
  • You consult as a freelance marketing strategist and run a small ecommerce store selling branded merchandise. The consultancy is service-based. The store is product-based with stock, shipping, and returns.

If you run one business with multiple revenue streams (a cafe that also sells cakes wholesale, for example) that is normally a single trade. The distinction matters because HMRC will challenge you if you try to split one trade into two to manipulate loss relief or avoid VAT registration. If in doubt, speak to your accountant before filing.

Which Self Assessment Pages Do You Need?

You report each trade on its own SA103S (Short) or SA103F (Full) page. You cannot report two trades on one set of pages.

If you file your return through accounting software like Xero, FreeAgent, or QuickBooks, the software will generate separate schedules for each trade. If you file manually through the HMRC online portal, you will see an option to add additional self-employment pages.

Here is the practical flow:

  • Trade 1: Complete SA103F (or SA103S if turnover is under £85,000 and your expenses are simple). Box 1.1 to Box 1.30 on the full pages.
  • Trade 2: Complete a second SA103F (or SA103S). Same box numbers. Different figures.
  • Summary page (SA100): The totals from each SA103 page feed into the main return automatically. Box 9 on the SA100 shows the combined self-employment profit or loss.

The key point: each trade gets its own turnover figure, its own expense breakdown, its own net profit or loss. HMRC sees them separately even though they appear on the same return.

Box-by-Box: Reporting Each Trade Separately

Using the SA103F (Full) pages as the example (most sole traders with multiple trades will need the full pages if either trade has significant expenses):

Trade 1: Your First Business

  • Box 1.1: Turnover (your total sales, excluding VAT if you are VAT registered).
  • Box 1.2: Construction Industry Scheme deductions (if applicable).
  • Box 1.3 to 1.10: Expenses by category. Do not split expenses between trades here. This page is for Trade 1 only.
  • Box 1.11: Total expenses.
  • Box 1.12: Net profit or loss (turnover minus expenses).
  • Box 1.13 to 1.30: Adjustments for capital allowances, business use of home, private use adjustments, and any other adjustments specific to Trade 1.

Trade 2: Your Second Business

  • Second SA103F page: Same box numbers. Different figures. Do not combine anything from Trade 1 onto this page.
  • Box 1.1: Turnover for Trade 2 only.
  • Box 1.11: Total expenses for Trade 2 only.
  • Box 1.12: Net profit or loss for Trade 2 only.

HMRC will add the two net profit figures together on the main SA100 return. If one trade makes a profit of £34,200 and the other makes a loss of £8,100, the combined figure on the SA100 is £26,100 profit.

Expense Allocation When Costs Are Shared

This is where most mistakes happen. If you use the same phone, internet connection, vehicle, or home office for both trades, you cannot claim the full cost against both.

You must apportion the expense on a reasonable basis. HMRC accepts a fair and consistent method. Examples:

  • Vehicle expenses: Keep a mileage log showing journeys for each trade. Claim the business proportion of fuel, insurance, and servicing against each trade based on the mileage split. If you drive 8,000 miles for Trade 1 and 2,000 miles for Trade 2 in a year, allocate 80% of the vehicle costs to Trade 1 and 20% to Trade 2.
  • Home office costs: If you use one room for both trades, calculate the total business use of the home (square footage or number of hours) and split it between the trades on a fair basis. A simple method: split 50:50 if both trades use the space equally, or by turnover proportion if one trade is significantly larger.
  • Broadband and phone: If you have one line used for both trades, split the cost. A 50:50 split is common. Or apportion by time spent on each trade.
  • Software subscriptions: If you pay for Xero or FreeAgent and use it for both trades, split the subscription cost. Most software platforms let you run multiple organisations under one account, so the cost is genuinely shared.

Document your method. HMRC can ask why you allocated 60% of the broadband cost to Trade 1 and 40% to Trade 2. If you can show the reasoning (Trade 1 generates 60% of your total self-employment income, for example) you are fine. If you cannot, they may disallow the expense against one trade.

Loss Relief When One Trade Loses Money

If Trade 1 makes a profit of £42,600 and Trade 2 makes a loss of £14,200, you can offset the loss against the profit from the other trade in the same tax year. This is same-year loss relief under s.64 ITA 2007.

The loss from Trade 2 reduces your total self-employment income on the SA100. Your taxable profit for the year becomes £28,400 (42,600 minus 14,200). You pay income tax and Class 4 NIC on that combined figure.

You can also carry the loss forward against future profits of the same trade, or claim it against other income (employment, dividends, savings) in the same year or the previous year. The rules are detailed and depend on whether you are claiming sideways loss relief or carry-forward relief. Speak to your accountant before making a claim. Once you submit the claim on your return, you cannot easily reverse it.

On the SA103F pages, you report the loss in Box 1.12 as a negative figure (put the loss amount in brackets or use the minus sign). HMRC's online system will recognise it and apply the loss against the other trade's profit automatically if you tick the correct box on the main SA100 page.

VAT Registration With Multiple Trades

The VAT registration threshold of £90,000 applies to the combined turnover of all your trades. You cannot keep one trade below the threshold and ignore the other. HMRC aggregates the turnover of all activities carried on by the same person.

If your landscaping business turns over £67,000 and your ecommerce store turns over £31,000, your combined turnover is £98,000. You must register for VAT even though neither trade exceeds £90,000 individually.

Once registered, you charge VAT on all sales from both trades. You can reclaim VAT on purchases for both trades. You file one VAT return covering all activities. The Flat Rate Scheme can still apply, but you use the rate for your main business activity or the highest-turnover trade.

Class 4 National Insurance With Multiple Trades

Class 4 NIC is calculated on your combined self-employment profits. The rates for 2025/26 are:

  • 6% on profits between £12,570 and £50,270
  • 2% on profits above £50,270

You do not get two separate Class 4 calculations. HMRC adds the profits from both trades together and applies the rates once. If Trade 1 makes £38,000 and Trade 2 makes £22,000, your combined profit is £60,000. You pay 6% on the first £37,700 (50,270 minus 12,570) and 2% on the remaining £9,730.

Class 2 NIC was abolished from April 2024. You no longer pay it regardless of how many trades you run.

Record Keeping for Multiple Trades

HMRC expects separate records for each trade. You do not need separate bank accounts, but you do need to be able to identify which income and expenses belong to which trade.

Practical approaches:

  • Separate bank accounts: The cleanest method. Open a second business bank account for the second trade. All income and expenses for Trade 2 go through that account. No apportionment arguments.
  • Separate accounting software organisations: In Xero or FreeAgent, create a separate organisation for each trade. Run each one independently. At year-end, export the reports and populate the relevant SA103 pages.
  • Spreadsheet tracking: If you use one bank account, tag every transaction by trade. Use a column in your bookkeeping spreadsheet for "Trade 1" or "Trade 2". Reconcile totals at year-end.

HMRC can ask for records for any trade going back up to 5 years (or longer if they suspect deliberate error). Keep all invoices, receipts, bank statements, and mileage logs for each trade separately.

Common Mistakes to Avoid

We see these errors regularly when reviewing returns for sole traders with multiple trades:

  • Combining turnover: Putting both trades' sales into one box. This inflates your turnover figure and means HMRC cannot see the individual performance of each trade. It also causes problems if one trade is VAT-registered and the other is not.
  • Double-claiming expenses: Claiming the full broadband cost against both trades. HMRC's computer will flag identical expense figures on two schedules. You will get a compliance check.
  • Ignoring the loss relief box: If you have a loss in one trade, tick the correct box on the SA100 to claim same-year relief. If you miss it, you can amend the return within 12 months, but it is easier to get it right first time.
  • Using the wrong form version: The SA103S (short) is for simple businesses with turnover under £85,000 and limited expenses. If either trade has capital allowances, business use of home, or adjustments for private use, you need the SA103F (full) pages. Using the short form when you should use the full form can mean you miss claiming legitimate deductions.
  • Forgetting the second schedule entirely: If you submit your return online and only complete one self-employment page, HMRC will not know about the second trade. You will need to amend the return, which costs time and can trigger a penalty if you miss the filing deadline.

What About Making Tax Digital?

From April 2026, sole traders with qualifying income over £50,000 must use MTD-compatible software to keep digital records and submit quarterly updates to HMRC. This applies to your combined self-employment income from all trades.

If you use Xero or FreeAgent for both trades, each trade will need its own quarterly update. HMRC will see separate schedules for each trade, just as they do on the annual return. The quarterly updates are not the final return. You still file the annual SA103 pages at year-end to confirm the figures.

For sole traders with combined income between £30,000 and £50,000, MTD for ITSA becomes mandatory from April 2027. Below £20,000, it is voluntary.

Final Checks Before You File

Before submitting your return, run through this checklist:

  • Do you have a separate SA103F or SA103S page for each trade?
  • Is the turnover on each page correct and exclusive of VAT?
  • Are the expense figures allocated correctly between trades?
  • Have you claimed the correct loss relief if one trade made a loss?
  • Is your combined turnover below the VAT threshold if you are not registered?
  • Have you kept records for each trade separately for at least 5 years?

If you are unsure about any of these points, speak to your accountant before hitting submit. Amending a return after filing is possible, but it is better to get it right first time.

Our ICAEW qualified team handles self assessment returns for sole traders with multiple trades across the UK. If you need help preparing your return or want to check whether HMRC would treat your activities as separate trades, get in touch.