Shared Ownership Calculator

Work out the monthly cost of shared ownership in England: share price, mortgage, rent on the unsold share, Stamp Duty both ways and staircasing.

2026/27 tax year

Property & Landlord
Personal
England

With shared ownership you buy part of a home (as little as 10% on some newer homes, up to 75%) and pay rent on the rest. Your monthly cost is the mortgage on your share, plus rent of up to 3% a year of the landlord's share on a new-build home (most landlords charge 2.75%; homes outside London, under Homes England's rules), plus any service charge. Enter the home's details to see the monthly total, the Stamp Duty both ways you can pay it, and what buying more later would cost.

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Staircasing: what buying more would cost

Prefilled from the figures above. Change the valuation to what the home is worth now: the price of a new share follows today's value, not what you paid.

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How the rent is worked out

The cap. For a new-build home's first sale, Homes England's Capital Funding Guide says the total initial rent "must not exceed 3% of the capital value of the unsold equity" (para 4.1.3), and encourages landlords to average no more than 2.75% across their new homes (4.1.4). That guide covers homes outside London; London homes come under the Greater London Authority's rules. gov.uk gives a 3% limit for new-build homes and says most landlords charge 2.75% (gov.uk: paying rent; Capital Funding Guide).
Worked example. A £400,000 home, 40% share: the landlord's 60% is worth £240,000, so 2.75% rent is £6,600 a year, £550.00 a month. With a 10% deposit, a 5% mortgage over 25 years on the other £144,000 is £841.81 a month, and with a £100 service charge the total is £1,491.81 a month.
Resale homes keep the rent the previous owner was paying; it is not reset to the cap.
Rent can rise at each review (usually yearly) and cannot go down. If you signed your lease before 12 October 2023 the most it can rise is RPI plus 0.5%. On a lease signed on or after that date it is either RPI plus up to 0.5% or CPI plus 1%, depending on the lease; under CPI plus 1%, if CPI has fallen by 1% or more the rent can be held at 0% (gov.uk; Capital Funding Guide 4.2.2).
Buying more cuts the rent in proportion to the landlord's remaining share: going from 40% to 70% halves the landlord's share from 60% to 30%, so the rent halves too.

Stamp Duty on shared ownership: the two routes

When a housing association, council or other qualifying landlord grants you a new lease, you choose how SDLT works (Finance Act 2003 Schedule 9; HMRC guidance). These figures use the SDLT rates for 2026/27 in England.

Market value election: pay once. SDLT is charged as if you bought the whole home, on the market value stated in the lease (para 2(4), or the open market premium under para 4 where the lease does not give you the freehold). Once that SDLT is paid, every later share you buy is exempt (para 4A(2)(a)). You make the election in the SDLT return, or by amending it within 12 months of the filing date, and you cannot withdraw it (para 2(3)).
Paying in stages. SDLT is charged on the premium you pay for your share and, as with any new lease, on the net present value of the rent. Later shares are exempt while your total share stays at or below 80% (para 4A(2)(b)). The purchase that takes you above 80%, and every one after it, is taxed.
First-time buyers (every buyer a first-time buyer who will live there as their only or main home, Sch 6ZA para 1(4)) can claim relief on either route (SDLTM29875). The £500,000 limit is tested on the full market value in the lease, not your share (Sch 9 para 15A(2)). With relief there is no SDLT on the first £300,000 and no SDLT on the rent (paras 15 and 15A(3)). HMRC's example: a 50% share of a £450,000 home with an election costs £7,500 (SDLTM29880). Relief never applies to staircasing (para 16; SDLTM29890).
Resales. If you buy an existing shared ownership home from its current owner, the lease is assigned rather than granted, so there is no election or stages choice: HMRC treats it like any lease assignment, and normal first-time buyer relief applies to the price you pay (SDLTM29875). The calculator's SDLT figures assume a new lease.
SDLT on the rent only arises on the stages route without first-time buyer relief (apart from any minimum rent under a para 4 election). It is 1% of the rent's net present value above £125,000, discounting each year's rent at 3.5000000000000004% (Schedule 5). RPI-linked increases are ignored (Sch 17A para 7(5)), so the calculator uses the starting rent for every year. That rule covers RPI only: on a CPI-linked lease (signed from 12 October 2023) expected increases in the first five years count, so this figure may understate the tax. On a £400,000 home with a 40% share and £6,600 rent over a 990-year lease, the NPV is about £188,571: £636 of SDLT on top of £700 on the share.
Going above 80% without an election. The lease and every staircasing purchase are linked, so the rate is set by the total you have paid for all of them, and this purchase pays its proportion of that tax at standard rates (SDLTM27065). A lease granted on or after 12 March 2008 is not retaxed (para 4B; SDLTM27065). Taking the example to 100% in one go when the home is worth £440,000 would cost £264,000 for the 60% and £6,974 in SDLT; going to 70% instead costs £132,000 and no SDLT.

Which is better? For a first-time buyer on a home worth £300,000 or less, the election costs nothing and removes any later bill, so there is little reason not to make it. Where the election would cost real money now, paying in stages defers or avoids it: you only pay again if you go above 80%, and then at the value at that time. Without first-time buyer relief the standard rates start above £125,000. You can compare both in the calculator or check a full purchase with the stamp duty calculator.

Not modelled: the 5% higher rates (gov.uk says any home you own must be sold by the time you complete your shared ownership purchase), a minimum rent stated in the lease under the para 4 election, and extra tax on earlier chargeable staircasing that a later purchase can trigger (FA 2003 s.81A).

Staircasing rules, and old versus new leases

Share sizes. You can usually buy shares of 10% or more at any time; some older leases need 25%, some newer ones allow 5%. If you bought on or after 1 April 2021 you may be able to buy 1% a year for the first 15 years. You cannot buy 2%, 3% or 4%, and unused 1% options do not roll over (gov.uk: buying more shares).
Price. For 5% or more, the price comes from a RICS valuation you pay for, and you must buy within 3 months of it. A 1% share is priced from the original price moved in line with the House Price Index, with no admin fee. Otherwise expect an admin fee of around £150 to £500. Improvements you had written permission for are left out of the value.
Ceilings. Most homes let you reach 100%. In some designated protected areas the limit is 80%, and Older Persons Shared Ownership stops at 75%, after which you pay no rent on the rest.
The 2021 model. For homes funded under Homes England's Affordable Homes Programme 2021 to 2026, the Capital Funding Guide sets a first share of 10% to 75% (it was 25% to 75%), 1% staircasing for the first 15 years, a minimum staircase of 5% (was 10%), a lease of at least 990 years and a 10-year initial repair period. The 5% minimum, 1% option and repair period also apply to homes funded under the Social and Affordable Homes Programme 2026 to 2036. Landlords may offer the new model on homes from the 2016 to 2021 programme that complete after 1 April 2021, but only all of it, not parts. Your key information document says which you have.
Initial repair period. Usually 10 years, only while you own less than 100%: the landlord pays for essential external and structural repairs, and you can claim up to a set amount a year (usually £500) for fixtures such as the boiler and pipes. After it ends, or on an older lease, every repair is yours whatever your share (gov.uk: repairs and home improvements).

Is shared ownership worth it?

It gets you in with a smaller deposit and mortgage. The calculator's comparison shows what the same deposit would need to borrow for the whole home. Against that:

You pay rent that can rise at each review (usually yearly) and cannot go down, plus service charges, and all repairs once any initial repair period ends.
Every shared ownership home is leasehold. A lease below 80 years becomes much more expensive to extend.
Until you own 100%, you must offer the home to the landlord first: it has a nomination period of 4, 8 or 12 weeks (depending on the lease) to find a buyer before you can sell on the open market. It does not apply in some cases, for example after the death of someone on the lease or a court order to transfer it.
You usually cannot sublet the whole home unless you own 100% or the landlord agrees.
To qualify, household income must be £80,000 or less (£90,000 in London), and you must be unable to afford a suitable home outright (gov.uk: who can apply).

This page covers England. Scotland, Wales and Northern Ireland run their own shared ownership schemes, and Scotland (LBTT) and Wales (LTT) have their own property taxes.

Frequently asked questions

How much rent do you pay on a shared ownership home?

Rent is a percentage of the value of the share the landlord still owns. On a new-build home the starting rent cannot be more than 3% of that share's value a year, and gov.uk says most landlords charge 2.75%. On a £400,000 home where you buy 40%, 2.75% of the landlord's £240,000 is £6,600 a year, or £550.00 a month. A resale home keeps the previous owner's rent.

Do you pay Stamp Duty on shared ownership?

Sometimes. When a housing association or other qualifying landlord grants you a new lease, you choose between paying once on the full market value (a market value election) or paying on the share you buy now and possibly again later. First-time buyer relief works on either route if every buyer is a first-time buyer moving in as their only or main home and the full market value is £500,000 or less: no SDLT on the first £300,000. On the stages route nothing more is due until your share goes above 80%. Buying a resale from another shared owner is taxed like any lease assignment, on the price you pay.

Should I make a market value election?

You can only elect when a qualifying landlord grants you a new lease, not on a resale. It suits you when SDLT on the full market value is nil or small, for example a first-time buyer (every buyer, moving in as their only or main home) on a home worth £300,000 or less, because once that SDLT is paid every later share is free of SDLT. If the election would cost real money now and you may never own more than 80%, paying in stages is usually cheaper. The election is irrevocable.

How much does it cost to staircase?

The price of the extra share is that percentage of the home's value now, not the price you paid. For a share of 5% or more the value comes from a RICS valuation you pay for; a 1% share follows the original price moved in line with the House Price Index. The landlord may charge an admin fee of around £150 to £500 (none on a 1% share). Add your legal fees, and possibly SDLT if your share goes above 80% and you did not make a market value election.

What is the minimum share you can buy in shared ownership?

On homes funded from 1 April 2021 the first share can be as low as 10% (up to 75%), but landlords need only offer the full range on some homes in a development, so check what the landlord offers; gov.uk says the share is usually between 25% and 75%. Later shares may be as small as 5%, or 1% a year for the first 15 years. Some older leases only allow further shares of 10% or 25%. You cannot buy a share of 2%, 3% or 4%.

Is shared ownership worth it?

It gets you a home for a smaller deposit and mortgage, but you pay rent on the rest, usually a service charge, and all repairs once any initial repair period ends, however small your share. Rent can rise at each review (usually yearly) and cannot go down. It works best if you can staircase over time; compare the monthly total with renting and with buying a cheaper home outright.