Shared Ownership Calculator

Q: Who is responsible for repairs in shared ownership?

Under the 2021 new model lease, the housing association covers essential repairs for the first 10 years, capped at £500 per repair. After 10 years, responsibility transfers fully to you. You always pay service charges for communal areas, typically £100-£200 per month for flats.

Calculate your total monthly cost, compare shared ownership vs buying outright, and model staircasing to full ownership. Based on the 2021 new model shared ownership lease.

Calculate your total monthly cost for a shared ownership property

Property value

Full market value of the property

Share to purchase

Typically 25-75% of the property

Deposit (% of your share)

Minimum 5% of your share, not the full property

Mortgage rate

Current shared ownership rates: 4-6%

Mortgage term

years

Rent rate (% of HA share/year)

Typically 2.75% of housing association share per year

Service charge

£/month

Average £100-£200/month for flats

Ground rent

£/month

New builds from 2022: £0 (peppercorn)

Location

Income limit: £80,000 (£90,000 in London)

Try another scenario

How to Use This Calculator

Monthly Cost tab

Enter the full property value, the share you want to buy (25-75%), your deposit (as a percentage of your share, typically 5%), mortgage rate, mortgage term, and the rent rate charged by the housing association on their share (typically 2.75% per year). The calculator adds an estimated service charge (£150/month default) to give your total monthly cost. Expand "More options" to adjust service charge, ground rent, and location.

SO vs Full Purchase tab

Compare buying a shared ownership share versus purchasing the same property outright with a standard mortgage. See the monthly cost difference, upfront deposit saving, stamp duty comparison, and long-term total cost. The calculator shows at what point (if any) shared ownership becomes more expensive than buying outright due to ongoing rent payments to the housing association.

Staircasing tab

Model buying an additional share of your property. Enter your current ownership percentage and how much more you want to buy (e.g., 10%). See the cost of the additional share, your new mortgage amount, the reduced rent, and the net monthly change. The calculator also shows the full path to 100% ownership in 10% steps.

Share your result

Every input is encoded in the URL. Click Share to send your exact scenario to a partner, housing association, or financial adviser.

The Formula

Shared ownership monthly cost combines three components:

Total Monthly Cost = Mortgage Payment + Rent to HA + Service Charge + Ground Rent

Mortgage Payment = P × [r(1+r)^n] / [(1+r)^n − 1]
where P = share value − deposit, r = monthly interest rate, n = total months

Your Share Value = Property Value × Share %
Deposit = Your Share Value × Deposit %
Mortgage = Your Share Value − Deposit

Monthly Rent to HA = (HA Share Value × Rent Rate) / 12
where HA Share Value = Property Value × (100% − Your Share %)

Stamp Duty (SDLT): paid on your share value (not the full property value)
if the property market value is £625,000 or less

The key advantage of shared ownership is that you only need a deposit on your share, not the whole property. For a 40% share of a £300,000 property, your deposit is 5% of £120,000 = £6,000, rather than 5% of £300,000 = £15,000. However, you pay rent on the portion you don't own, which is an ongoing cost with no equity return.

Example

Sarah — Key Worker, £40,000 salary, Birmingham

Sarah is a teaching assistant earning £40,000. She wants to buy a 40% share of a £300,000 two-bedroom flat in Birmingham. She has £6,000 saved for a deposit and qualifies for shared ownership (household income under £80,000).

Monthly Cost tab

Property value£300,000

Share purchased40% (£120,000)

Housing association share60% (£180,000)

Deposit (5% of share)£6,000

Mortgage amount£114,000

Mortgage payment (4.5%, 25 years)£634/month

Rent to HA (2.75% of £180,000)£413/month

Service charge£150/month

Total monthly cost£1,197/month

Sarah's total upfront cost is just £6,000 (deposit) plus stamp duty and legal fees. Buying the same flat outright with a 10% deposit (£30,000) and full mortgage would cost around £1,650/month — but Sarah doesn't have £30,000 saved and her income wouldn't qualify for a £270,000 mortgage.

Staircasing example

After 5 years, Sarah buys an additional 10% share. The property is now valued at £320,000 (modest growth), so the extra 10% costs £32,000. Her rent drops from £413/month to £344/month because the HA now owns only 50% instead of 60%. Over time, Sarah can staircase to 100% ownership.

FAQ

What is shared ownership and how does it work? ▼

Shared ownership is a government-backed scheme that helps people who cannot afford to buy a home outright. You buy a share of a property (between 25% and 75%) and pay rent on the remaining share to a housing association. You need a mortgage and deposit only for your share, making it much more affordable upfront. You can increase your share over time through a process called "staircasing" until you own 100%. The scheme is available on new-build homes and some resale properties through housing associations registered with Homes England.

Who is eligible for shared ownership in the UK? ▼

To qualify for shared ownership, your household income must be £80,000 or less (£90,000 in London). You must be a first-time buyer, a previous homeowner who cannot afford to buy now, or an existing shared owner looking to move. You should not be able to afford to buy a home suitable for your needs on the open market. Priority is given to existing social tenants, military personnel, and people with a local connection to the area. The scheme is open to anyone aged 18 or over. Source: GOV.UK and Homes England.

How much rent do I pay on the housing association share? ▼

Rent is typically set at 2.75% of the housing association's share of the property value per year. For example, if the HA owns 60% of a £300,000 property (£180,000), your annual rent is £180,000 × 2.75% = £4,950, or £412.50 per month. Under the 2021 new model shared ownership lease, rent increases are capped at CPI + 1% per year (previously RPI + 0.5%). This cap provides more predictable costs over time. As you staircase and buy more shares, your rent reduces proportionally.

What is staircasing and how does it work? ▼

Staircasing is the process of buying additional shares in your shared ownership property. Under the 2021 new model, you can staircase in increments as small as 1% for the first 15 years (previously the minimum was 10%). The cost is based on an independent valuation at the time of staircasing, not the original purchase price — so if the property has increased in value, you pay the higher price. Each staircasing step requires a valuation (typically £200-£500) and legal fees. When you reach 100%, you own the property outright and no longer pay rent to the housing association. You may also be able to extend your lease or acquire the freehold at that point.

Who is responsible for repairs in shared ownership? ▼

Under the 2021 new model shared ownership lease, the housing association is responsible for the cost of essential repairs for the first 10 years of ownership, capped at £500 per repair. This is a significant improvement over the old model where the buyer was responsible for all repairs from day one despite not owning 100%. After the 10-year initial repair period, responsibility transfers fully to you. You are always responsible for cosmetic and minor repairs, and you pay service charges for communal areas (typically £100-£200 per month for flats). Source: Homes England new model lease.

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