Shared Ownership Mortgage Calculator
Found a shared ownership home? Enter the price, the share you are buying, your deposit, the rent and the service charge, and see what 32 lenders could lend on your share. It is a shared ownership affordability calculator that counts the rent and service charge the way lenders count them.
Lender criteria last reviewed September 2026.
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If the housing association’s own calculator comes out tight, an adviser may be able to set out your circumstances to them, but the housing association decides. This tool estimates what lenders could lend, based on their published criteria.
Homes England calculator or lender affordability?
Shared ownership is checked twice, and the two checks answer different questions. The housing association’s adviser works out which share you should buy, following the Homes England method. The lender then decides how much it will lend on that share. You need to pass both, and one can come out higher than the other.
| Compared on | Housing association (Homes England method) | Mortgage lender |
|---|---|---|
| The question | Which share should you buy? | How much will it lend on that share? |
| The rent | Projected five years ahead with inflation | Today’s rent, taken off as a monthly commitment |
| The test | Mortgage payment no more than about 30% of your net income after rent, service charge and commitments, with a minimum surplus left over. In London, the GLA’s guide tests total housing costs (mortgage, rent and service charge) against 40% of net household income instead. | The lender’s own income multiples and stress-tested interest rate, capped at its maximum loan-to-value of the share |
| Buying too small a share | Can fail: you are expected to buy the largest share you can afford | Many lenders need at least a 25% share; above that, buying a smaller share isn't a concern for the lender |
| Where to get it | From the housing association’s appointed adviser | This tool, across 32 lenders |
Homes England no longer publishes a calculator of its own, so each adviser uses their own tool built on its method. If that assessment comes out tight, an adviser may be able to set out your circumstances to the housing association, but the housing association decides, so treat it as a guide rather than a straight pass or fail.
How much are shared ownership monthly repayments?
Your monthly cost has three parts: the mortgage on the share you buy, rent on the share you don't, and the service charge. On a £300,000 home with a 40% share and a 5% deposit, that is about £717 for the mortgage, £413 rent and £100 service charge: roughly £1,230 a month.
| Share | Deposit | Mortgage | Mortgage a month | Rent a month | Service charge | Total a month |
|---|---|---|---|---|---|---|
| 25% | £3,750 | £71,250 | £448 | £516 | £100 | £1,064 |
| 40% | £6,000 | £114,000 | £717 | £413 | £100 | £1,230 |
| 50% | £7,500 | £142,500 | £896 | £344 | £100 | £1,340 |
| 75% | £11,250 | £213,750 | £1,345 | £172 | £100 | £1,617 |
| 100% (buying outright) | £15,000 | £285,000 | £1,793 | £0 | — | £1,793 |
Illustration only: a £300,000 home, a 5% deposit on the share, a repayment mortgage at 5.75% over 25 years, first-year rent at 2.75% a year of the share you don't own and a £100 a month service charge. On 5 October 2026 the cheapest fixes for a 95% loan were about 5.5% and the average about 6.3%. Rounded to the nearest pound.
A smaller share means a smaller mortgage but more rent, so the total moves less than the mortgage does. Three things change it after you move in: the rent goes up once a year (by up to CPI plus 1% on leases granted from 12 October 2023, or RPI plus 0.5% on older ones), the service charge can rise, and your fixed rate ends after two or five years. The shared ownership rent guide explains how the yearly increase works, and the calculator below projects all three.
What will it cost over the years?
Before you check what lenders could lend, see the running costs: rent, service charge and mortgage together, year by year.
Share value £75,000
5% of your share
Your figures
Illustration, not a personal recommendation- Total spend over 25 years
- £407,564
- First-year monthly cost
- £1,064
- Share owned at the end
- 25%
- Equity at the end
- £123,045
Assumes a 5.75% mortgage over 25 years, a lease signed now, with rent rising CPI + 1% (CPI at a long-run 2%), and house prices growing 2% a year (they can fall). Change any of these, add staircasing and compare with renting in the full calculator.
Open the full calculatorWhat this calculator takes into account
Works from your share
Share value and loan are derived from the full price and the percentage you are buying. Loan-to-value is measured against the share.
Counts rent and service charge
Both are deducted as committed spending at every lender, so the estimate reflects them.
Only lenders that do shared ownership
32 of the 57 lenders we check lend on shared ownership purchases. Each is capped at its headline maximum loan-to-value of the share; some lenders cap flats lower, which the check doesn't yet apply.
From the listing to a lender answer
Most shared ownership homes are found on Share to Buy, Rightmove or the housing association’s own site. Every listing shows the full price, the share on offer and the monthly rent, and the Key Information Document adds the service charge. Copy those four figures in, add your deposit and income, and the tool does the rest.
Worked example
A £40,000 salary buying a 40% share of a £250,000 home with a £10,000 deposit, £300 a month rent and a £120 service charge. On a live run on 2 September 2026, thirty lenders returned a figure on the £100,000 share. Lenders that do not lend on shared ownership purchases were left out. The mortgage needed was £90,000, so the answer came down to each lender’s loan-to-value limit on the share rather than income.
Example only. Your figures depend on your income, commitments, region and the lenders’ criteria on the day.
What you will need
- The full purchase price of the home
- The share you are buying (usually 10% to 75%)
- Your deposit — on the share, not the full price
- The monthly rent on the unsold share
- The monthly service charge
- Your income and any credit commitments
All five property figures are on the housing association’s listing or Key Information Document. Not sure how the two-stage assessment works? Read the shared ownership affordability guide. Buying in London? The London edition covers the £90,000 income cap and London-sized rent.
Run My Shared Ownership CheckWhat usually sets the answer: the share, not your income
On a standard purchase your income is normally what limits the loan. On shared ownership it usually is not. You are borrowing against a slice of the home, so the loan is small next to the income behind it, and the lender’s loan-to-value ceiling on the share — commonly 95%, and 90% at some lenders — is what you hit first. Your income only becomes the limit on larger shares, or where the rent and service charge are high.
| Full price | Share | Share value | Max loan | Deposit | Income for it to bind (after rent and service charge) |
|---|---|---|---|---|---|
| £250,000 | 25% | £62,500 | £59,375 | £3,125 | £19,551 |
| £280,000 | 35% | £98,000 | £93,100 | £4,900 | £26,894 |
| £300,000 | 40% | £120,000 | £114,000 | £6,000 | £31,483 |
| £400,000 | 50% | £200,000 | £190,000 | £10,000 | £48,922 |
| £560,000 | 40% | £224,000 | £212,800 | £11,200 | £57,729 |
At a 95% ceiling on the share. The last column is roughly the income at which a lender capping you at about 4.5 times your income, after taking off the rent (2.75% a year on the share you don't buy) and a £100 a month service charge, would start to limit you instead. Below it, income is what limits you. Lenders that use a stress-tested affordability model may need a little more or less, and a higher service charge raises it.
Two things follow. The deposit is far smaller than people expect — £3,125 on a £250,000 home at a 25% share — and the number that decides whether you can proceed is usually the rent and service charge, because those are deducted as committed spending before any lender looks at the loan. That is why this calculator asks for both, and why two homes at the same price and share can give different answers.
Illustration, not advice, and not every lender lends at 95% of a share. The check shows each lender’s own answer on your figures.
Remortgaging a shared ownership home
When your deal ends you can remortgage like any other owner, with two differences: only lenders that lend on shared ownership will look at it, and your landlord has a say. The loan-to-value is measured against your share at today’s value, so if prices have risen your loan-to-value may have fallen.
- The landlord approves the lender and the terms. Your landlord has to agree the new lender and mortgage terms in writing before the mortgage starts, or the lender doesn't get the protection of the lease's mortgagee protection clause. On the newer leases it must decide within 28 days, and Homes England says refusals are very rare. Permanent changes to an existing mortgage need consent too, so ask your landlord what it needs even if you're staying with your lender.
- You tell the landlord about the new mortgage. The lease asks you to notify the landlord within a month of any new mortgage or charge, and it can charge a reasonable fee.
- Borrowing more is limited. Lease covenants normally allow extra borrowing only to buy more shares, to pay for essential repairs the lease requires, or to buy out a co-owner, not for a car, a holiday or other debts. Your total borrowing can't be more than your share is worth.
- Remortgaging to staircase. Buying 5% or more (10% on older leases) needs a RICS valuation, valid for three months; 1% steps on the newer leases are priced from the house price index instead. Your rent falls in proportion, and the lender counts the lower rent when it works out what it will lend. Stamp duty may be due if you go above 80%.
To see what lenders could lend on a bigger share, run the check with the share you’d own after staircasing and the lower rent. The staircasing calculator shows the cost of each step, and the remortgage affordability guide covers how lenders test a remortgage. Selling instead? See selling a shared ownership home.
Frequently asked questions
Is this the Homes England affordability calculator?
No. Housing associations have an adviser run an assessment following the Homes England method to set the share you should buy. This tool estimates what mortgage lenders could lend on that share, with your rent and service charge counted. If the Homes England figures come out tight, an adviser may be able to set out your circumstances to the housing association, but the housing association decides, so treat them as a guide rather than a pass or fail.
Why does a shared ownership calculator need the rent and service charge?
Lenders treat rent on the unsold share and the service charge as committed spending and deduct them before working out your maximum loan. Leaving them out overstates what you can borrow, which is a common mistake in shared ownership affordability.
How is the loan worked out?
Share value = full price × share percentage. Mortgage = share value − deposit. Your loan-to-value is measured against the share, not the full price, and each lender caps it at its own maximum, usually 90% or 95% of the share (some cap flats or new-build flats lower, at 85%).
Do all lenders offer shared ownership mortgages?
No. Of the 57 residential lenders we check, 32 lend on shared ownership purchases. Some only lend when you staircase to 100%, and some do not lend in Scotland, Wales or Northern Ireland. The tool leaves those out automatically.
Can I remortgage a shared ownership home?
Yes, with a lender that lends on shared ownership. Your landlord has to approve the lender and the mortgage terms in writing before the new mortgage starts, or the lender doesn't get the protection of the lease's mortgagee protection clause; on the newer leases the landlord must decide within 28 days. You can usually only borrow more to buy more shares, to pay for essential repairs the lease requires, or to buy out a co-owner, and your total borrowing can't be more than your share is worth.
Does it run a credit check?
No. It uses lenders' own published affordability calculators and criteria, with no credit search and no application.
Do I need a mortgage adviser for shared ownership?
In practice, yes. Housing associations ask for a financial assessment from a qualified adviser before they accept a reservation, and the lender choice matters more here than on a standard purchase because fewer lenders offer it and the rules differ. This tool gives you the lender answer to take into that conversation, so you arrive with an estimate of which lenders may fit and roughly what they could lend.
Results are indicative and based on lenders’ published calculators. They are not a mortgage offer or advice.
See what you could borrow on your share
Free, about 5 minutes, no credit search.
Start My Free CheckHow this calculator works, and when it was last checked
- Method
- Share value = full price x the share you are buying. The mortgage needed = share value - deposit, and loan-to-value is measured against the share rather than the full price, so each lender's LTV cap (usually 90% or 95% of the share) applies to that figure. Rent on the unsold share and the service charge are treated as committed spending and deducted before the income assessment, which is why both are asked for.
- Lender criteria last verified
- — The lenders our calculator checks were reviewed lender by lender against each lender's published criteria, giving 32 of the residential lenders we check that lend on a shared ownership purchase, including which decline outside England and which only lend once you own 100%.
- Sources
- Lender published criteria for shared ownership (per lender)
- Who checked it
- Reviewed by Phillip Wakeling-Smith, CeMAP-qualified mortgage adviser.
Results are an estimate for general information, not a quote, an offer of credit, or advice. Your own figures depend on a lender's full assessment of your circumstances.