Rent Increase Calculator: What the New Rent Really Costs (2026)
Work out what a rent increase actually costs: the pound and per-cent change, the extra rent over a year, how it compares with ONS rent and CPI data, landlord tax on the extra rent, and tenant affordability.
Embed this calculator on your website — free, no sign-up, always on the current rates. Paste the code below; the widget links back to this page so your visitors can read the full guide.
<iframe src="https://landlordtaxlab.co.uk/embed/rent-increase-calculator" title="Rent Increase Calculator — landlordtaxlab.co.uk" width="100%" height="760" style="border:0;max-width:960px" loading="lazy"></iframe>
Terms: keep the “Powered by” link intact; rates come from our data, updated when HMRC changes them; general information, not advice.
The rent increase notice checker tells you whether a rent increase is LEGALLY valid. This calculator answers the other question — what the new rent actually costs, and whether it is a reasonable figure by the numbers the market and HMRC use. Enter the current and proposed monthly rent and it works out the pound and percentage change, the extra rent over a full year, how that rise compares with the latest official rent and inflation data, the tax a landlord pays on the extra income, and whether a tenant’s income would clear the usual referencing check on the new figure.
How the numbers are built
The increase is simply new rent minus old rent, shown in pounds and as a percentage of the current rent. Multiplying the monthly difference by 12 gives the annualised extra rent — the figure that actually lands on a landlord’s tax return, and the one a tenant should budget against rather than the monthly figure alone.
Comparing the rise with the market
The calculator checks the percentage increase against the Office for National Statistics’ Private Rent and House Prices index, the official measure of what rents are doing across the UK. In the release covering the 12 months to July 2026 (published 19 August 2026), average UK rent rose 3.7% to £1,393 a month — England ran a little hotter at 3.8%, Wales at 4.5%, and Scotland much cooler at 1.7%. The tool also checks the rise against CPI inflation (2.9% for the same 12 months, published the same day) so you can see whether the increase is simply tracking the cost of living or running ahead of it. Neither figure is a ceiling on what a landlord can charge — only Scotland has a formal challenge route on the amount, covered below — but both give a tenant real grounds for a market-rent argument, and a landlord evidence for setting a defensible figure.
The landlord’s tax on the extra rent
Higher rent is higher property income, taxed at your marginal rate: 20%, 40 or 45% for the 2026/27 tax year (the current England & Northern Ireland bands from the same data behind our other calculators; Scottish-resident landlords pay under Scotland’s own bands instead — use the rental income tax calculator for those). A rise that pushes total income past a band threshold only pushes the part above it into the higher rate, and can also shrink the Section 24 mortgage-interest credit if it tips a basic-rate landlord over the line. This tool applies one flat rate to the extra rent for a quick estimate; it does not model expenses, the £1,000 property allowance or other income, which the full calculator does.
Scotland: a different process for challenging the amount
England’s route is the one the notice checker tests: Form 4A, at least 2 months’ notice, once every 12 months, with a market-rent challenge before the new rent starts. A Scottish private residential tenancy runs on different law. The landlord must give at least 3 months’ written notice and cannot increase rent more than once in any 12-month period; instead of a market-rent challenge, a tenant who disagrees can refer the notice to Rent Service Scotland within 21 days of receiving it. A rent officer then sets the rent by assessing the open-market rate for comparable homes — the figure can go up as well as down — aiming to decide within 40 days. Either side can ask for a review within 14 working days of the decision, and appeal on from there to the First-tier Tribunal for Scotland (Housing and Property Chamber). None of this applies in England or Wales, and this page does not cover Wales’ own Renting Homes (Wales) Act rules separately.
Can the tenant actually afford it?
Add a gross household income and the calculator applies the common 30× referencing rule — the same convention the rent affordability calculator covers in full — to show the income the new rent needs, and whether the figure entered clears it. It is a market convention some agents vary, not a legal threshold.
ONS rent and CPI figures: "Private rent and house prices, UK: August 2026" and "Consumer price inflation, UK: July 2026", both published 19 August 2026, read 13 September 2026 (the September 2026 rent release, due 16 September 2026, was not yet out). Scotland process: mygov.scot "Rent increases if you have a private residential tenancy" and "Increasing the rent for a private residential tenancy", read 13 September 2026. Tax bands: taxdata.py, checked 2026-08-29. England and Wales notice rules: gov.uk "Renters’ Rights Act: an overview for landlords". General information, not advice.
Asked constantly
The extra annual rent (the monthly rise x 12) is taxed at your marginal income tax rate — 20, 40 or 45% for 2026/27 in England, Wales and Northern Ireland. This calculator applies one flat rate for a quick estimate; the rental income tax calculator models expenses, the property allowance and Section 24 alongside your other income.
Compare the percentage rise with the latest ONS Private Rent and House Prices figures — UK, England, Wales and Scotland run at different rates, and Scotland in particular has been rising much more slowly than England. Neither figure caps what a landlord can charge; it is evidence for a market-rent argument, not a rule.
Refer the notice to Rent Service Scotland within 21 days of receiving it. A rent officer assesses the open-market rent for comparable homes and sets the figure — which can be higher or lower than what the landlord proposed — usually within 40 days, with a review and then an appeal to the First-tier Tribunal for Scotland available after that.
No — for England, use the rent increase notice checker, which tests the notice against Form 4A, the 2-month notice period and the once-a-year rule. This page only works out the money once you already have a rent figure to compare.
The ONS Private Rent and House Prices release measures what rents are actually doing across the UK; CPI measures overall consumer price inflation, of which rent is only one part. A rent rise can run above one and below the other.
No — it's a common referencing convention some letting agents use (others use 36x or less), not a statutory test. The rent affordability calculator covers the alternatives, including guarantors and rent in advance.
Doing this every quarter, not just once?
Keep the same figures all year instead of re-typing them: rent and expenses per property, the Section 24 finance costs and the MTD quarterly totals, in one workbook.
Landlord Tax Lab stays free. We also sell the Landlord Tax Pack: one Excel workbook for up to 10 properties that logs rent and expenses per property, maps every line to its SA105 box, keeps Section 24 finance costs out of the expense boxes, and rolls up the MTD quarterly totals. £19 once — no subscription.
Disclosure: we make and sell the Tax Pack — this is our own product, not a paid recommendation. It does not file anything with HMRC and it is not tax advice; filing goes through you, your accountant or software on HMRC’s compatible-software list.
Sources
The primary documents this page is built from. Links checked 5 September 2026.
- Private rent and house prices, UK — Office for National Statistics
- Consumer price inflation, UK — Office for National Statistics
- Rent increases if you have a private residential tenancy — mygov.scot
- Increasing the rent for a private residential tenancy — mygov.scot