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Estimate buy-to-let cash flow, rental Income Tax, vacancy and interest-rate scenarios.
Compare annual buy-to-let rent with mortgage interest, entered running costs and an illustrative rental Income Tax estimate. Then see how a chosen void period and an interest-rate increase could affect annual cash flow. This is a personal residential-landlord illustration, not a tax return, lender stress test, valuation or investment recommendation.
The form starts with two illustrative rental properties and an £85,000 employment salary. Valid URL inputs or consented saved browser values take priority. The result panel reflects whichever inputs are currently active.
The estimate assumes an individual residential property business. Enter only eligible rental expenses and the allowable relief amount for replacement domestic items (not its gross purchase price). Other taxable income, pension relief, brought-forward property losses, joint ownership, company ownership, mortgage fees/capital repayments and property-specific rules are not fully modelled. Section 24 credit is capped in this illustration; the actual HMRC calculation has further rules.
· Tax-year assumptions: 2026/27.
Headline result (estimate)
Portfolio health check
Figures are scenario-based estimates and depend on your inputs.
Total net cash flow
£2,551/ year
Rental Income Tax (estimate)
£19,059
Portfolio value
£0.83M
Copy a summary or a link. Links exclude amounts by default.
Applied equally to each property in the Vacancy and Combined scenarios; other entered costs remain unchanged.
Applied to each estimated loan balance (market value × LTV), assuming interest-only borrowing, in the Rate shock and Combined scenarios.
Stress scenarios adjust rent and/or interest assumptions. This is an estimate and does not model tenancy turnover costs, refinancing fees, or lender-specific underwriting.
Net cash flow after allocated estimated rental Income Tax; negative values are shown below zero.
| Property | Net cash flow / year |
|---|---|
| Apartment 1 (City) | £-265 |
| House 2 (Suburbs) | £2,816 |
Annual profile estimates. NI is on salary; rental income can affect Self Assessment student-loan repayments.
| Item | Estimate |
|---|---|
| Income Tax | £40,491 |
| National Insurance on salary | £3,711 |
| Student loan estimate | £0 |
The same entered portfolio under base, vacancy, interest-rate shock and combined assumptions.
| Scenario | Net cash flow / year |
|---|---|
| BaseSelected | £2,551 |
| Vacancy | £186 |
| Rate shock | £-7,409 |
| Combined | £-9,774 |
Base vs stress scenarios.
| Scenario | Net cash flow | After-tax cash yield | Rental Income Tax |
|---|---|---|---|
| BaseSelected | £2,551 | 0.31% | £19,059 |
| Vacancy | £186 | 0.02% | £17,124 |
| Rate shock | £-7,409 | -0.89% | £16,569 |
| Combined | £-9,774 | -1.18% | £14,634 |
All figures are estimates based on the inputs above and current calculator settings. They do not constitute tax or financial advice.
For an individual residential landlord, residential finance costs are generally not deducted from property income. A basic-rate tax reduction may apply, but it is limited to the lowest of eligible finance costs, property-business profits and adjusted total income above the Personal Allowance; it cannot create a refund. This page approximates those limits and does not model brought-forward losses or every Self Assessment rule.
The reduction is not automatically 20% of all interest: the eligible amount and your total tax liability can cap it. Check the linked HMRC calculation guidance for your circumstances.
Lenders may use an Interest Cover Ratio (ICR) or another rental-coverage test when assessing a portfolio. The required ratio, stressed rate and treatment of tax can vary by lender, product, borrower and property, so the calculator's stress setting is a scenario input rather than a lender rule.
Loan-to-Value (LTV) is the estimated loan balance as a percentage of entered property value. Here it is used only to estimate the extra annual interest under a rate shock, assuming the loan is interest-only and the balance is approximately value × LTV. No “healthy” target LTV is prescribed; actual balances, repayment basis and lender criteria vary.
This page’s “after-tax cash yield” divides its estimated annual net cash flow by current property value. It includes the entered mortgage interest and costs, estimated tax and student-loan increment; it is not the same as gross yield, lender ICR or a return on equity because loan principal and acquisition costs are not collected.
Pension contributions can sometimes lower Adjusted Net Income, which may change the marginal tax rate applied to rental profits. The impact depends on your pension scheme and allowances.
Pension Efficiency ToolFor some portfolios, holding property via a Limited Company can change how interest and profits are taxed compared with personal ownership. Incorporation can also involve SDLT and CGT costs.
Landlord Tax ToolIf your portfolio has tighter interest cover (ICR), you may want to review cash flow resilience. One approach can be reducing debt exposure, depending on your objectives and transaction costs.
CGT CalculatorProperty profit can affect your Adjusted Net Income and Personal Allowance. Above £100,000, the allowance generally tapers by £1 per £2 of adjusted net income above the limit. The resulting marginal-rate interaction varies by region and reliefs; this calculator does not model all adjusted-net-income deductions.
Estimate your marginal rateThese HMRC and GOV.UK sources support the tax, property and energy-efficiency explanations referenced by this scenario calculator.