Calculate your monthly mortgage, rent on the unsold share, service charge and total monthly cost for any share percentage.
Your Shared Ownership Details
£
%
Typically 10–75% for new builds; 25–75% for older properties
£
Typically 5–10% of your share value
%
%
Housing associations typically charge 2.75% p.a. — confirm with your provider
£
Covers maintenance of communal areas, building insurance, management fees
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Monthly Mortgage
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Monthly Rent
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Total Monthly
Full Property Value—
Your Share Value—
Your Deposit—
Mortgage Amount—
Monthly Mortgage Payment—
Unsold Share Value—
Monthly Rent on Unsold Share—
Monthly Service Charge—
Total Monthly Cost—
Total Annual Cost—
Results are illustrative. The rent rate is indicative — confirm the exact rate with the housing association. Service charges vary significantly by property. This calculator does not include stamp duty, legal fees or other purchasing costs. Always get independent financial and legal advice before purchasing.
How Shared Ownership Costs Work
Shared ownership is a hybrid of buying and renting. You take out a mortgage on the share you buy (typically 10–75% of the property) and pay subsidised rent to the housing association on the remaining share they retain.
The Three Monthly Costs
Mortgage payment — a standard repayment or interest-only mortgage on your share minus your deposit
Rent — charged by the housing association on the share they own, typically at 2.75% of that share's value per year, paid monthly. This rate increases annually, usually by RPI + 0.5%.
Service charge — covers maintenance of communal areas, building insurance, management fees and sometimes ground rent. Ranges from £50/month for a small house to £400+/month for a managed flat in a city centre.
Worked Example
Example: £280,000 Property, 40% Share (£112,000)
Share value (40% of £280,000)
£112,000
Deposit (10% of share)
£11,200
Mortgage (4.8%, 25 yrs, repayment)
£553/month
Unsold share (60% of £280,000)
£168,000
Monthly rent (2.75% of £168,000 ÷ 12)
£385/month
Service charge
£150/month
Total monthly cost
£1,088/month
Staircasing: Buying More Shares
Staircasing allows you to buy additional shares in your home — typically in minimum 10% increments. Each time you staircase, the price is based on a new market valuation of the full property, not what you originally paid. As house prices rise, staircasing becomes more expensive — but your equity also grows.
When you reach 100% ownership, you no longer pay rent to the housing association. Some leases allow full staircasing in one step; others require incremental purchases.
In England, you must have a household income below £80,000/year (£90,000 in London), be a first-time buyer or former homeowner who can no longer afford to buy outright, not currently own a home, and be unable to afford a suitable home on the open market. You must be at least 18 and have the right to live in the UK. Some properties are restricted to key workers or people with a local connection.
Yes. You can staircase to buy additional shares, typically in 10% tranches. Each tranche is priced at the current market value — not what you originally paid. Once you reach 100%, rent to the housing association stops. Some older leases allow staircasing to a maximum of 80% before full ownership; newer (2021+) leases typically allow 100%.
Housing associations typically charge 2.75% of the unsold share's value per year, charged monthly. So if the unsold share is worth £168,000, annual rent is £4,620 (£385/month). This rate usually increases each year by RPI + 0.5%. Always confirm the exact rent rate and escalation terms with the housing association before purchasing.
Yes. The housing association usually has a nomination period (4–8 weeks) where they can find a buyer for your share. If they cannot, you can sell on the open market — but the buyer must meet shared ownership eligibility criteria unless you have staircased to 100%. The process takes longer than a conventional sale and involves additional legal work.
For properties built under the new model lease (from April 2021), the minimum initial share is 10%. For older properties it is typically 25%. Most properties have a maximum initial purchase of 75%, with staircasing available thereafter. The minimum share for a specific property is set by the housing association.
You have two options: pay SDLT only on the initial share (and again when staircasing to 80%+), or elect to pay on the full market value upfront (market value election) and pay nothing more on future staircasing. First-time buyers qualify for first-time buyer SDLT relief. Your solicitor can calculate which option is cheaper for your specific situation.