CT600 Box by Box: The Income Section (Boxes 145-205) Explained
The income section of the CT600 is where you tell HMRC how much your company earned. Getting these boxes right is critical — errors here affect your entire tax calculation.
Box 145: Turnover / Business Income
This is your company's gross trading income for the period. Include:
- Sales revenue
- Fees for services
- Commission income
Don't include: Investment income, property income, or chargeable gains — those go in separate boxes.
Box 150-165: Trading Income and Net Profit
- Box 150: An indicator box for banks, building societies, insurance companies and other financial concerns that do not have a recognised turnover figure. If your company falls into this category, tick this box and leave box 145 blank. Almost all trading companies with ordinary sales revenue use box 145 and leave box 150 blank.
- Box 155: Your company's taxable trading profits. This is not the same as your accounting profit — it starts with the profit in your accounts and applies tax adjustments: add back disallowable expenses (depreciation, client entertaining) and deduct capital allowances. The result is the figure HMRC taxes. Your tax computation should include a detailed calculation.
- Box 160: Trading losses brought forward from earlier periods that you are setting against this year's trading profit (box 155). Only enter enough to cover the profit — don't enter more than box 155.
- Box 165: Net trading profits — box 155 minus box 160. This is calculated automatically. If box 160 equals box 155, enter 0. If box 155 is blank, leave this blank too.
Box 170-175: Non-Trading Loan Relationships and Annual Payments
- Box 170: Bank, building society or other interest, and profits from non-trading loan relationships. Combine all non-trading loan relationship credits and debits into a single net figure. For most small companies this is simply bank interest earned on deposits. Example: your business account earned £250 interest — enter 250.
- Box 172: Tick if the figure in box 170 has been reduced by a non-trading loan deficit carried back from a later accounting period. Rare — most small companies leave this blank.
- Box 175: Annual payments not otherwise charged to Corporation Tax and from which Income Tax has not been deducted. These are a specific legal category of regular payments (for example, certain patent royalties payable to individuals) — not normal business expenses like rent, salaries, or supplier invoices. Most small companies leave this blank.
Box 190: Property Business Income
Income from UK or overseas property your company owns:
- Rental income (net of allowable property expenses)
- Lease premiums
- Service charge income
This is the profit from property, not gross rent — deduct mortgage interest, repairs, management fees, and other allowable property expenses first.
Box 195-200: Other Income
- Box 195: Non-trading gains on intangible fixed assets
- Box 200: Tonnage tax profits (shipping companies only)
- Box 205: Income not falling under any other heading
Box 205 is a catch-all for miscellaneous income that doesn't fit elsewhere — certain compensation receipts, post-cessation receipts, non-exempt UK dividends from other resident companies, etc.
Box 235: Profits Before Other Deductions and Reliefs
This is the net sum of boxes 165 to 205 and 220, minus boxes 225 and 230. It represents your total profits from all sources after applying brought-forward deficits against non-trading income — but before charitable donations, group relief, and other deductions further down the form.
Taxpipe calculates this automatically.
Common Mistakes
- Including VAT in turnover — Box 145 should be net of VAT (if VAT-registered)
- Putting gross rent in Box 190 — this should be net property profit, not gross rental income
- Forgetting bank interest — even small amounts of bank interest count as non-trading income (Box 170)
- Missing the loss boxes — if you have brought-forward trading losses, entering them in box 160 reduces your trading profit and lowers your tax bill
Filing your CT600? Taxpipe guides you through every box with clear explanations. £59, no accountant needed.