Published by LetLogiQ · Page updated 20 September 2026 · Calculation basis & updates
How to calculate buy-to-let cash flow
Start with rent actually collected after empty periods. Deduct running costs and the full mortgage payment to find pre-tax cash. Then deduct estimated tax. Taxable profit is a separate calculation: repaying mortgage capital reduces cash but is not a rental expense for tax purposes.
Yield and cash-on-cash ROI answer different questions
Gross yield compares scheduled annual rent with the purchase price. Net yield deducts voids and operating costs, before finance and tax. Cash-on-cash ROI compares annual cash with the cash you put into the purchase, including setup costs and the opening reserve. A high gross yield does not necessarily mean positive cash flow.
Replace every planning allowance with a property-specific figure
Enter realistic maintenance, insurance, management, compliance and accounting costs. Allow for vacancies and choose interest-only or repayment finance. Use the stress scenarios below to see whether the property still produces cash when rent falls or the mortgage rate rises.
Buy-to-let worked example
This fixed illustration uses the calculator’s starting assumptions, not your edited inputs: England, a £200,000 additional property, £50,000 deposit, 5% interest-only borrowing and a 25-year term. Rent of £1,200 per month, two weeks’ voids and standard operating allowances. Personal ownership, £35,000 other annual income and the England/Wales/Northern Ireland income-tax basis. Remaining costs use the editable planning estimates.
- Annual scheduled rent
- £14,400
- Annual running costs
- £2,150
- Annual estimated tax
- £839
- Monthly cash after tax
- £280
Rounded figures are illustrative. The live calculator above provides the full cost and tax breakdown.
Common questions
How much profit will I make from a buy-to-let?
There is no single typical answer. Use achievable rent, all recurring costs, your actual finance terms and your tax circumstances. The result is an estimate for the assumptions entered, not a guaranteed return.
Does this calculator include tax?
Yes. Personal ownership estimates the additional income tax associated with the property, including the modelled residential finance-cost tax reduction. Company ownership estimates corporation tax; tax on taking money out of the company is excluded.
Does the calculator include house-price growth?
No. Cash profit, cash-on-cash ROI and payback exclude property appreciation, selling costs and tax on a sale.