| Overview |
Capital allowances for sole trader clients are claimed via the SA103F (Self-Employment Full) supplementary schedule in BrightTax. The capital allowances calculator is built into the schedule and handles pool calculations, annual investment allowance (AIA), writing down allowances (WDA), and disposals automatically based on the asset details you enter.
| Before You Begin |
- You must use SA103F (Full) — capital allowances are not available on the SA103S (Short) schedule.
- Have the asset details ready: description, date of purchase or disposal, cost or proceeds, and any private use percentage.
- Ensure the SA103F schedule has been added to the return via the Summary tab before starting.
| Accessing the Capital Allowances Calculator |
- Open the ITR and navigate to the SA103F schedule via the Summary tab.
- Switch to Edit mode using the bottom-left toggle.
- Click View/Edit Capital Allowances Details within the self-employment schedule.
- The Capital Allowances Calculator opens, showing the available asset pools.
| Available Asset Pools |
| Pool Type | What It Covers |
|---|---|
| Main Pool | Plant and machinery at the standard 18% WDA rate |
| Special Rate Pool | Assets qualifying for the 6% WDA rate — integral features, long-life assets, thermal insulation |
| Single Asset (Private Use) | Assets with an element of private use — e.g. a car used partly for business and partly personally |
| Adding an Asset Addition or Disposal |
- In the Capital Allowances Calculator, locate the relevant pool.
- Click View/Edit under that pool.
- Click Create to add a new entry.
- Tick either Asset Addition or Asset Disposal as appropriate.
- Enter the asset details: description, date, cost or proceeds.
- For single asset private use items, enter the private use percentage.
- Click Save. The calculator will update the pool balance and calculate the allowances automatically.
- Repeat for each additional asset. Click Save again when all assets have been entered.
| ✔ Tip: You can add multiple assets across multiple pools. Work through each pool in turn, adding all additions and disposals before moving on. |
| Single Asset Private Use Pool |
Where an asset is used partly for business and partly personally — most commonly a motor vehicle — it must be entered in the Single Asset Private Use pool rather than the Main Pool. Enter the private use percentage (e.g. 25% private use) and BrightTax will automatically restrict the allowances to the business proportion.
| ⚠ Important: From the May 2026 update, validation in the Single Asset Private Use pool now works correctly for all tax years. If you previously encountered issues saving entries in this pool, these have been resolved — re-enter any affected data. |
| Reviewing the Capital Allowance Summary |
After entering all assets, click Capital Allowance Summary from the left-hand navigation within SA103F to view a summary of all pools, additions, disposals, AIA claimed, WDA calculated, and the total allowances feeding into the self-employment profit calculation.
| Frequently Asked Questions |
Q: Where is the Annual Investment Allowance (AIA) claimed?
A: AIA is calculated automatically by BrightTax based on the assets entered in the Main Pool and Special Rate Pool. You do not need to enter AIA separately — the calculator applies it to eligible additions first.
Q: Can I claim capital allowances on a car in the Main Pool?
A: Cars cannot be added to the Main Pool — they must go in the Single Asset Private Use pool if there is any private use, or in the Main Pool only if there is zero private use and the car is not a low-emission vehicle. Contact support if you are unsure which pool applies to a specific vehicle.
Q: The capital allowance figure looks different to what I expected — how do I check the calculation?
A: Go to the Capital Allowance Summary page within SA103F to see a full breakdown of how the allowance has been calculated, including opening balances, additions, disposals, and the applicable rates.
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