Shared ownership calculator
With shared ownership you buy a share and pay rent on the rest. See the deposit, the mortgage and the full monthly cost.
How this is calculated
Your share's value is the full market value times the share. The deposit is taken off that and the rest is the mortgage.
Rent is the yearly percentage times the value of the share you do not own, divided by twelve.
The total is the mortgage payment, the rent and the service charge.
Rates used · 2026/27
| Rent | charged on the share you do not own |
| Staircasing | buying more shares later, at the value then |
| Service charge | usually paid in full by you |
| Rent rate | set by the provider |
Last checked July 2026. Source: HMRC and gov.uk.
Worked example
Buying a 40% share of a £300,000 home is £120,000. With a 10% deposit the mortgage is £108,000, costing £600.30 a month at 4.5% over 25 years. Rent at 2.75% on the unowned £180,000 adds £412.50 and the service charge £150, so £1,162.80 a month in total.
Common questions
How does shared ownership work?
You buy a share of the home with a mortgage and pay rent to a housing provider on the rest. You can usually buy more shares later.
Can I own 100% in the end?
Often yes, by staircasing up to full ownership, though some homes cap the share you can own.
Do I pay all the service charge?
Usually yes, even though you own only part of the home.
Is shared ownership cheaper than renting?
Sometimes, sometimes not. Compare the total monthly cost here with the rent on a similar home.