Shared Ownership Calculator

How shared ownership works

You buy a share of a home with a mortgage, and pay rent to a housing association on the share you don't own. Because your deposit and mortgage are based on the share rather than the whole property, the amount you need up front is far smaller. That is the entire point of the scheme, and for many people it is the difference between buying and not.

The trade-off is that you carry two housing costs at once, plus a service charge, and the rent continues for as long as you own less than 100%. Your mortgage payment is fixed for the length of your deal. The rent is reviewed every year and rises with inflation, so the two move apart over time. That is why the ten-year view above matters more than the first month's figure.

The stamp duty decision, and why it is the important one

When you buy a new-build shared ownership home you choose, once, how to pay the transaction tax. The choice cannot be undone, and it is made by ticking a box on a form your solicitor files.

Pay in stages. Tax is worked out on the share you buy, plus an amount reflecting the rent you will pay over the life of the lease. This is almost always cheaper on the day. Nothing further is due while your share stays at or below 80%. Go above 80% and tax becomes payable — and it is worked out on the combined value of every purchase you have made, not on the slice you are buying at the time.

Make a market value election. Tax is worked out on the full value of the property, as though you had bought all of it outright. It costs considerably more on the day. But it settles the matter permanently: you will never pay again, however far you staircase.

The gamble is straightforward to state and hard to answer. If you never go above 80%, paying in stages wins. If you eventually buy your home outright, the election usually wins, sometimes by thousands. Nobody knows in advance which of those they will do, and the tax system asks you to guess on the day you move in.

Three things that catch people out

You stop being a first-time buyer immediately. The relief applies to your first purchase only. Buy a 25% share and you have used it — even buying more of the same home later, you count as an existing owner. If your first-time buyer relief would cover the full market value, making the election costs you nothing and protects you permanently. That is the one case where the answer is obvious.

The election is only available on a new build. It can be made when the lease is first granted and never afterwards. Buying a resale, you inherit whatever the first buyer decided. If they made the election, you benefit from it. If they didn't, you cannot make it now.

Staircasing costs more as prices rise. Each tranche is priced at the property's value at the time you buy it, not what you originally paid. In a rising market the share you didn't buy gets further away each year.

Where you are buying changes the rules

England. Shares from 10% to 75%, rent capped at 3% of the landlord's share and usually set at 2.75%. Stamp Duty Land Tax applies.

Wales. Shares typically from 25% to 75%, through around 30 housing associations. Land Transaction Tax applies instead, with a nil-rate band of £225,000 — considerably higher than England's £125,000 — but no first-time buyer relief at all. There is no standard Welsh rent rate, so you have to get it from the listing or the landlord.

Northern Ireland. The scheme is Co-Ownership, which has run since 1978. Shares from 50% to 90%, rent set at 2.5% of Co-Ownership's share, staircasing in 5% steps, and a property value limit of £215,000. Stamp Duty Land Tax applies, the same as England.

Scotland does not have shared ownership in this form. Its equivalent is LIFT shared equity, where the government takes a stake of between 10% and 40% and no rent is charged on it at all. The sums on this page would give you a meaningless answer, so Scotland is deliberately not offered here rather than being fudged.

Common questions

Is shared ownership cheaper than renting?

Often in the first year, and less reliably after that. Your mortgage payment is fixed but the rent and service charge both rise, while market rents rise too. The honest comparison is not month one but the whole period, set against the equity you build — which the comparison above works out for you.

Can I get a mortgage on a shared ownership home?

Yes, but from a smaller group of lenders. The lease structure and the rent element need specialist underwriting, so a broker who has done it before is worth more here than usual.

What happens to the rent when I buy more shares?

It falls in proportion to the share you now own. Buy your way from 25% to 50% and the rent drops by a third, because the landlord's share has gone from 75% to 50%. It is not recalculated from the property's current value.

Do I pay ground rent?

Almost certainly not, if your lease was granted on or after 30 June 2022. The Leasehold Reform (Ground Rent) Act 2022 requires ground rent on your share to be a peppercorn, meaning nothing. Older leases can still carry one. Be wary of any calculator that adds a ground rent figure by default.

Who pays for repairs?

Under the shared ownership lease model introduced in 2021, the landlord covers essential repairs for the first ten years, capped per repair. Older leases generally leave everything to you from day one, despite you owning only part of the home. Check which lease you are being offered.

Can I sell whenever I want?

Yes, but the housing association usually has a period in which to find a buyer before you can market it openly, and shared ownership resales can take longer than ordinary sales. Factor that in if you might need to move quickly.

Assumptions

The mortgage is a repayment mortgage at a single rate for the whole term; in practice you will remortgage several times and the rate will change. Rent is taken at its opening level and raised each year by the figure you enter. Stamp duty on the rent element uses the statutory 3.5% discount rate over a 99-year lease, with the rent held at its opening level — which is how it is filed on the day, since future inflation is unknown. Staircasing tax is estimated on the combined value of the linked transactions. Valuation fees, legal fees, mortgage fees and buildings insurance are not included. Eligibility, income caps and local connection rules are not checked.

This tool gives estimates to help you ask better questions. The stamp duty election cannot be reversed, so confirm the figures with your conveyancer before you decide. Rates checked against HMRC, GOV.UK, the Welsh Revenue Authority, the Northern Ireland Department for Communities and Homes England on 31 July 2026, and reviewed every April.

Related tools

• Take-home pay calculator — what actually lands in your account each month, which is the figure a lender will work from.
• Salary sacrifice calculator — worth checking before a mortgage application, since sacrificing salary lowers the income a lender sees.