Landlord Cashflow Calculator, UK 2026/2027
When I moved in with my partner, I kept my flat.
Suddenly, I found myself a landlord. The rent would just about cover mortgage and expenses, I thought. In fact, now I divert hundreds of pounds a month from my employment income to the property. (See my personal cashflow here.)
This is the calculator I wish I had back then. No spreadsheet, but an intuitive graphical representation of your money flow.
Tax on rental income, in addition to that on your regular employment, can be significant. The restriction of tax relief on mortgage interest (section 24) only complicates matters further. Don't get caught out.
Perhaps you are moving in with your partner like me, or are moving cities, or inherited a property. Or maybe you have spare cash and are eyeing a buy-to-let. In any case, understanding the cashflow implications before committing is crucial. With this calculator, you can explore different scenarios and instantly see how letting in addition to your regular employment might impact your monthly bottom line. The calculator is based on English rates for the tax year 2026/2027. Read about example cashflow situations, illustrating how to use the calculator effectively.
Inputs
Employment Income (before tax, minus salary sacrifice, plus benefits-in-kind)
monthly: or annually:
Rental Income
monthly rent:
Rental Expenses (tax deductible expenses eg. maintenance, service charge, tenancy creation costs)
monthly:
Rental Mortgage
total monthly mortgage payment:
of which interest:
of which principal repayment:
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Monthly Cashflow
drag or click values to edit
Notes
Marginal tax rate:
Income over £100k: You might lose Government subsidized child care
Rental & sole trader income above £20k: You will need to sign up for making tax digital in the future (step-wise introduction: 2026 over £50k, 2027 over £30k, 2028 over £20k)
Tax on rental income is not automatically deducted like PAYE for tax on employment income. You should set aside £ from your rental income every month to be able to pay the tax when it becomes due and avoid surprises.
The calculation considers 2026/27 Class I NI contributions and tax bands for England, deductible expenses (or property allowance if larger) and mortgage interest relief. This simplified calculation does not consider, for example:
- Other income and taxes (such as dividend, saving, capital gains, stamp duty)
- Rent-a-room scheme for renting out a room in your main residence
- Self-employment
- Buy-to-let through a limited company
- Personal circumstances that may vary and lead to different outcomes
This is a simplified model for illustrative purposes only. This is not financial advice and should not be relied upon as such. Always consult with a qualified financial advisor or accountant for personalised advice.
Privacy: Your inputs into the calculator are processed locally and not transmitted over the internet.