Buy-to-let and property income on your CT600: rent, expenses and losses

Short version. Enter rental income before expenses in Property rental income. Enter costs once in the matching trading or property expense rows. If a cost is shared, divide it between the two sections using your own allocation. We use your figures to calculate the trading and property results separately. Mortgage interest goes in Interest payable, not in property running costs.

1. Rental income is not the same as taxable property profit

Use the rental income belonging to the accounting period, not simply the cash received. Company landlords use accounting principles and a property business is normally separate from a trade. See HMRC PIM1020.

The wizard's Turnover field is for trading sales. Enter rent separately, without subtracting agent fees or other costs. Our gross-entry accounts combine trading sales and rent in their turnover line. The Corporation Tax return keeps trading turnover separate from the taxable property result. Do not enter the same rent in both current-year fields.

2. Buy-to-let companies and property SPVs

If the company only lets property, select that business type. Trading sales are hidden, but expense rows remain available. Enter raw materials or consumables, staff costs, depreciation and Other charges where relevant. We assign operating costs and disallowable expenses to property without asking for a second allocation.

In gross entry, Other charges excludes charitable donations. Enter donations separately and we include them once in the accounts. Interest and capital allowances also have their own fields.

3. A company that both trades and lets property

Use Trading income and expenses for sales and trading costs, and Property income and expensesfor rent and letting costs. Each has materials, staff costs, depreciation and Other charges. Do not enter the same cost in both sections. We combine the figures for the company's annual accounts.

For a £1,000 shared cost that you allocate 60% to trading and 40% to property, enter £600 in the trading row and £400 in the property row. There is no separate property-share question.

Use your allocation of shared costs. We do not ask for evidence or an allocation-method explanation. Check deductibility using HMRC's property expense guidance.

Enter property disallowable expenses and any qualifying property intangible-amortisation deduction underProperty tax treatment. These are tax adjustments to costs already entered, not additional expenses. See HMRC's business-use guidance.

This cost allocation does not add support for splitting capital allowances between trading and property. Read capital allowances for landlords before entering a claim.

4. Using your own property tax calculation

The calculated base starts with rent, subtracts property running costs, adds property disallowable expenses, then subtracts any qualifying property-amortisation deduction. It is before capital allowances, balancing charges and loss relief.

You can enter your own amount in Your property tax base. Include your property tax adjustments in that figure. A blank field uses our calculation, 0 is an explicit zero base and a negative amount is a loss. This changes the property tax calculation, not the gross accounts. Keep the trading and property expense entries separate even when you use your own property tax base.

Select Use the calculated figure to remove the override. Rental income and expense entries stay in place.

Older net-only drafts: keep the net field or choose Enter gross rent and separate expenses. On upgrade, the old net figure becomes the visible manual tax base. Enter the actual rent and costs, then choose the calculated figure if that is what you want. We cannot reconstruct gross rent from a net figure, so legacy net-only accounts retain that limitation.

The upgrade has no undo action. If you selected it by mistake, enter the actual rent and costs. You can retain your own property tax base.

5. Where mortgage interest goes

Enter company mortgage and loan interest in Interest payable. Do not deduct it again in rent, running costs or the manual property base. Company borrowing costs use the loan-relationship rules, not the personal-landlord rules. See HMRC PIM2052.

An unused borrowing deficit is not a property loss. Read about non-trading loan relationship deficits and brought-forward deficits.

6. Worked examples

These examples have no interest, donations, capital allowances or loss relief.

• Property only: £30,000 rent, £6,000 running costs and £500 disallowable costs give a £24,500 property tax base. Enter £30,000 rent and £6,000 expenses, not £24,000 net rent.
• Trading and property: £100,000 sales with £14,000 trading costs and £1,500 trading add-backs. Separately enter £30,000 rent, £6,000 property costs and £500 property add-backs. Trading profit before other adjustments is £87,500 and the property base is £24,500.
• A letting loss: £1,000 rent and £6,000 deductible property costs give a £5,000 loss. Keep rent positive and enter costs separately.
• A manual calculation: entering £8,000 as the property base in the mixed example uses £8,000 instead of £24,500. It does not change the £87,500 trading remainder or rewrite the accounts.

7. Property losses and prior-year accounts

Enter unused property losses from earlier periods in Property losses brought forward. The engine applies the supported loss treatment and shows the remaining balance in the computation. A current-period loss box is not the same as the unused balance.

Enter previous-year trading turnover and rental income beside the corresponding current-year fields. The property expense rows also have their own comparatives. Previous-year donations are separate from Other charges and do not affect the current-year tax calculation.

Companies House often publishes only balance-sheet figures. We prefill what is available and you enter the rest. For a property-only company, prefilled company income and costs appear in the property fields. For a mixed company, divide any prefilled company totals between trading and property without duplicating them. If a prefilled Other charges total includes donations, split it before adding a separate donation comparative.

Changing business type clears financial entries after a warning. We fetch available prior-year figures from Companies House again. You enter anything the published accounts do not contain.

8. Scope and official guidance

This route supports UK property within our micro-entity filing service. Overseas property and unsupported capital-allowance treatments need a different filing route. Selling an investment property is not rental income. See chargeable gains on property disposals.

You decide whether the company qualifies for the accounts format. Read about micro-entity thresholds and the two-year rule and associated companies.

This is general guidance, not a check of entitlement to a deduction. We use the figures and treatment you enter. Check the linked HMRC guidance or seek advice if you are unsure about an expense or allocation.