Other income not taxable on a CT600: income in your accounts that is not chargeable to Corporation Tax
Short version. Keep the full income figure in your accounts. If part is not chargeable to Corporation Tax, record that part as Other income not taxable in the tax computation. Only the taxable remainder belongs in CT600 box 205, alongside any taxable UK dividends that belong there.
1. Accounts income and box 205
The CT600 is the company's Corporation Tax return. Box 205 covers taxable profits or gains without another heading, including non-exempt UK distributions. Interest, rent, turnover and disposals have separate treatments. HMRC's Company Tax Return guide explains these categories. The accounts figure can be larger than the taxable figure.
2. Choosing the treatment
This field records the treatment your company has adopted. It does not decide whether income is taxable. An entry labelled FX, exchange gain or unrealised movement is not automatically outside the charge. The underlying transaction matters. Read our guide to exchange differences on shares and its official sources for that particular scenario.
Use the adjustment only for an amount already included in Income not falling under any other heading. It cannot exclude turnover or another income row, and it is not an expense or a loss claim. The amount must be whole pounds and cannot exceed that full income figure.
3. What the computation shows
The computation removes the full accounts other-income credit from the trading calculation. It shows the taxable part as income taxed separately and the excluded part as Less: Other income not taxable. It then adds back only the taxable part when calculating total profits. This prevents the same income being taxed twice.
HMRC's Corporation Tax computations format, page 7, footnote 17 expects details describing the income and why it is not taxable. You can enter a short explanation of up to 200 characters. It is optional and leaving it blank does not block filing.
4. Worked example
Your accounts include £4,000 of other income. You treat £3,000 as not chargeable and £1,000 as taxable. Keep £4,000 in the accounts income field and enter £3,000 in Other income not taxable. With no taxable UK dividends, box 205 shows £1,000.
The figures you entered stay the same. The calculated Corporation Tax charge may fall, increasing profit after tax or reducing the loss after tax. If tax was already nil, those figures stay the same. You can compare the accounts and computation before submitting.
5. How to enter it in SimpleCompanyTax
SimpleCompanyTax supports this optional adjustment for trading and property-only companies. In the filing wizard:
- Go to Financial data and find Income.
- Select + Add other income if its row is closed.
- Enter the full accounts amount in Income not falling under any other heading.
- Under Tax adjustments, enter the excluded part in Other income not taxable.
- A Description row appears once you enter an amount. Add a short note if you wish. It is optional.
- On Review, check Less: Other income not taxable, the taxable remainder and the generated CT600 box 205. A fully excluded amount contributes nothing to box 205.
- Review your filing documents and complete the usual declaration before submitting.
For a long accounts period with two CT600s, the adjustment is divided between the returns with the related accounts income. Check both computations. You do not enter the whole deduction twice.
This is general filing guidance, not tax advice. You prepare the figures and choose their treatment. Read the other income and cashback guide if you need to identify the correct entry row.