Unsupported Tax Features
Clear Books Tax is designed for straightforward filings. Learn what advanced CT600 features aren't supported and how to work around limitations using existing fields.
Clear Books Tax is designed for straightforward company filings. Some advanced CT600 features are not yet supported as dedicated fields. This guide explains what's not available and how to work around common situations.
What Clear Books Tax Supports
Clear Books Tax handles the most common filing scenarios:
- Trading income (Box 145, 155, 165)
- Annual Investment Allowance (Box 735) - up to £1,000,000 per year
- Trading losses - brought forward and carried forward
- Interest income (Box 170)
- Disallowable expenses - entertaining, fines, depreciation add-back
- Marginal relief calculations
- Property rental income (Box 190)
- Annual Investment Allowance (Box 735) - for equipment and fixtures
- Property losses - brought forward and carried forward
- Interest income (Box 170)
- Disallowable expenses - depreciation add-back
- Marginal relief calculations
Workarounds Using Existing Fields
For many situations, you can achieve the correct tax payable using Clear Books Tax's existing fields. The key is the Other adjustments field and Annual Investment Allowance.
How to Access These Fields
In the Tax Computation - Current Year section header, you'll see a Show all link on the right side. Click it to reveal all available adjustment fields:
Show all
After clicking, it changes to "Hide empty". This reveals several fields including:
| Field | Box | Use For |
|---|---|---|
| Other adjustments (add if positive, deduct if negative) | — | Any adjustments not covered by other fields |
| Less: Annual Investment Allowance | 735 | 100% first-year allowances on qualifying equipment |
| Add back: Depreciation | — | Automatically populated from P&L |
| Add back: Disallowable expenses | — | Client entertaining, fines, penalties |
When to Use Specialist Software
Clear Books Tax may not be suitable if your company has:
- Complex capital allowances - multiple pools, balancing charges, or short-life assets
- R&D activities - claiming R&D tax credits
- Group structures - group relief claims between companies
- Northern Ireland trading - separate NI profits calculation
- Investors' relief or BADR - Box 215 or Box 220 gains
- Full CT600 software (TaxCalc, Taxfiler, etc.)
- Using an accountant who can file on your behalf
- HMRC's own CT600 filing service (basic but comprehensive)
Last updated: April 2026
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