£UK Calculators

Shared Ownership Calculator

Shared Ownership lets you buy a share of a home, usually between 10% and 75%, with a mortgage on that share, and pay subsidised rent on the rest. This calculator works out your estimated total monthly cost: mortgage, rent and service charge together.

Shared ownership calculator

Your home

The property’s full market value, and the share you’re buying (usually 10% to 75%).

The percentage of the home you'll own outright.

Your mortgage

The rate on the mortgage for your share, not the full property.

Rent and service charge

Set by your landlord's lease, commonly around 2.75% to 3%. Check your specific offer.

Covers maintenance of communal areas, buildings insurance and management. Varies by property.

Your estimated monthly cost

Mortgage, rent and service charge combined, based on the figures you entered.

£1,269a month

Cost breakdown

Share cost£120,000
Unowned share value£180,000
Mortgage payment£736.90
Rent£412.50
Service charge£120.00
Total monthly cost£1,269.40

A typical deposit is around 10% of the share cost, so roughly £12,000 here, though many lenders accept as little as 5%. Rent usually rises each year in line with your lease’s rent review formula, so expect this figure to increase over time. All figures are rounded to the nearest penny.

This is an estimate, not financial or tax advice.

Figures are calculated from published HMRC and gov.scot rates and thresholds for the 2026/27 tax year. This calculator is independently built and is not affiliated with, or endorsed by, HMRC or the UK Government. It assumes a single, stable salary with no other income, and does not account for every personal circumstance (such as Marriage Allowance, Gift Aid, or benefits in kind). For advice on your own situation, speak to your employer's payroll team, a regulated financial adviser, or HMRC directly. See the full disclaimer.

How Shared Ownership works

Shared Ownership, sometimes called "part buy, part rent", is a government-backed scheme aimed at people who can't afford to buy a home outright on the open market. You buy a share of the property, typically between 10% and 75% of its full market value, using a mortgage on that share plus a deposit. You then pay rent to the landlord, usually a housing association, on the share you don't own, along with a service charge covering things like buildings insurance and maintenance of shared areas.

Over time, you can buy further shares in your home, a process known as staircasing, right up to full ownership in most cases. As your share grows, the rent on the remaining unowned portion falls, reaching zero once you own the property outright.

How rent on the unowned share is worked out

Unlike Income Tax or National Insurance, there's no single government-fixed rent percentage for Shared Ownership. It's set out in your specific lease, and reputable guides commonly cite figures in the region of 2.75% to 3% of the unowned share's value per year. That's why this calculator asks you to enter the percentage yourself rather than assuming one: check the exact figure in the specific property's offer documents. Rent is also reviewed annually and typically rises, commonly by up to RPI plus 0.5% on older leases, or CPI plus 1% on leases granted from October 2023 onwards, so expect the figure shown here to increase over time.

Staircasing: buying more of your home over time

Staircasing means buying additional shares in your home after your initial purchase. Older leases typically require a minimum 10% share each time you staircase, while many newer leases allow smaller steps, including buying as little as 1% a year for the first 15 years on some schemes. Each time you staircase, your mortgage and deposit needs increase, but your rent falls, since it's only charged on the share you still don't own.

Example calculations

These worked examples come straight from the calculator above, so the figures match exactly what you'd see entering the same numbers yourself.

First home, 40% share

£300,000 home · 40% share

£1,269a month

London flat, 25% share

£450,000 home · 25% share

£1,662a month

Smaller home, 50% share

£200,000 home · 50% share

£894a month

Frequently asked questions

How does Shared Ownership work?

You buy a share of a home, usually between 10% and 75% of its full market value, using a mortgage on that share plus a deposit. You pay rent to the landlord, usually a housing association, on the remaining share you don't own, along with a service charge for maintenance of communal areas and buildings insurance. Over time, you can buy further shares in a process called staircasing, which reduces your rent as your ownership grows.

How is the rent on the unowned share worked out?

There's no single government-fixed rent percentage; it's set out in your specific lease. Reputable guides commonly cite figures around 2.75% to 3% of the unowned share's value per year, which is why this calculator asks you to enter it rather than assuming one number. Check the exact percentage in the property's specific offer documents before relying on any estimate.

Does the rent stay the same every year?

No, it's reviewed annually and typically rises. For leases granted before 12 October 2023, the rent can usually increase by up to the Retail Price Index (RPI) plus 0.5% a year. For newer leases granted from that date onwards, it's typically the Consumer Price Index (CPI) plus 1%. This calculator shows today's rent based on the percentage you enter; it doesn't project future increases, so expect the real figure to rise over the years you live there.

What is staircasing?

Staircasing is buying additional shares in your home after your initial purchase, gradually increasing your ownership, sometimes up to 100%. Older leases typically require a minimum 10% purchase each time you staircase, while many newer leases allow smaller steps, including buying as little as 1% a year for the first 15 years on some schemes. As your share grows, the rent on the remaining unowned share falls, reaching zero once you own the property outright.

How much deposit do I need for Shared Ownership?

Your deposit is based on the value of the share you're buying, not the full property value, which is one of the scheme's main affordability advantages. Lenders usually ask for at least 5% to 10% of the share cost, so on a £120,000 share, that's typically £6,000 to £12,000, rather than a deposit based on the home's full value.

Can I sell a Shared Ownership home?

Yes. You can sell your share at any time, though the housing association usually has a set nomination period, commonly 4, 8 or 12 weeks depending on your specific lease, to try to find a buyer themselves before you can market it on the open market. If you own less than 100%, you'll typically need a valuation to confirm the current value of your share before selling.

Is Shared Ownership worth it compared to renting or a full mortgage?

It depends on your circumstances. Shared Ownership can make homeownership achievable with a smaller deposit and mortgage than buying outright, but you're paying rent on top of a mortgage, plus a service charge, and total housing costs aren't always lower than renting the equivalent property outright. It's worth comparing this calculator's total monthly cost figure against the market rent for a similar home, and factoring in that you build equity in your own share as you pay down the mortgage, which renting doesn't offer.

Methodology and assumptions

This calculator assumes:

  • A standard repayment mortgage on the share you're buying, using the same fixed-rate amortization formula used across UK lending, at the rate and term you enter.
  • Rent is calculated as the percentage you enter, applied to the value of the share you don't own, and shown at today's rate. It does not model future annual rent increases.
  • Service charge is whatever you enter, since it's set per property and this calculator has no way to look it up for a specific home.
  • The typical deposit figure shown is illustrative only, based on 10% of the share cost; some lenders accept as little as 5%.
  • All figures are rounded to the nearest penny.

Sources

This calculator is based on the general structure of the government-backed Shared Ownership scheme; the rent percentage is set by individual leases, not a published government rate:

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