Shared ownership calculator
Find out exactly what shared ownership costs each month. Enter your share, the full property value and the rent on the unowned portion — then see how it compares to buying outright or renting privately, and what staircasing looks like over time.
Shared ownership gets you onto the property ladder with a smaller deposit and a lower mortgage, but it is more complex than either renting or buying outright. The total monthly cost is often higher than people expect once service charges are included. Before committing, get the full service charge history for the last three years and ask specifically whether any major works are planned. A surprise service charge bill is one of the most common shared ownership complaints.
How staircasing works
Staircasing means buying additional shares in your property over time, typically in chunks of at least 10%. Each time you staircase the property is revalued and you pay the current market price for the additional share. As your share grows, the rent element reduces. At 100% you own the freehold outright in most cases.
The resale restriction
When you sell a shared ownership property the housing association typically has the right to find a buyer for up to eight weeks. If they cannot, you can sell on the open market — but only to eligible shared ownership buyers if you own less than 100%. This can limit your buyer pool and affect sale speed.
Is it worth it?
Shared ownership makes sense when you cannot raise enough deposit to buy outright, the property values in your area are growing, and you plan to stay long enough to staircase. It is less attractive when service charges are very high, the property is in an area of low growth, or you need flexibility to move quickly.
Deposit requirements
You only need a deposit on your share, not the full property value. A 5% deposit on a 40% share of a £250,000 property is £5,000. This is a major advantage for buyers who cannot save a large deposit but can afford the monthly payments. Some lenders offer specialist shared ownership mortgages at competitive rates.
Please note: All figures are estimates based on the inputs provided. Actual mortgage rates, rent charges and service charges will vary by housing association, lender and property. Shared ownership rules differ between England, Scotland, Wales and Northern Ireland. This calculator covers England. Always seek independent financial and legal advice before entering a shared ownership agreement. This is not financial advice.
Calculator results are estimates based on the information you enter and the assumptions built into the tool. They are illustrative only and should not be relied upon as accurate projections. Rates, thresholds and rules change regularly; always verify figures with an appropriate professional or official source before acting on them.
What is shared ownership?
Shared ownership is a government-backed scheme that allows you to buy a percentage share of a property – typically between 10% and 75% – and pay subsidised rent on the remaining share owned by a housing association. You take out a mortgage on the share you buy, and the rent on the unowned share is typically set at around 2.75% of its value per year.
Over time, you can buy additional shares in the property (a process called staircasing) until you own 100%, at which point the rent stops.
How to use this calculator
Full property value: The total market value of the property as set by the housing association.
Share percentage: The percentage you are buying – the minimum is typically 10%, the maximum 75% at initial purchase (some schemes allow more).
Mortgage rate and term: The rate and term on the mortgage you are taking on the purchased share.
Monthly rent percentage: The annual rent rate on the unsold share – typically 2.75% of the unsold share value, divided by 12 for the monthly amount.
Service charge: The monthly service charge or estate charge on the property. This varies significantly, from £50 to £500 per month, depending on the development. Always confirm the exact figure before proceeding.
Reading the result: The calculator shows your total monthly housing cost, mortgage payment, rent on the unsold share, and service charge combined. This total is the figure to compare against alternative options such as renting privately or buying outright.
The true cost of shared ownership
The headline appeal of shared ownership is the lower deposit and mortgage required on a smaller share. The full monthly cost – once rent and service charge are included – is often higher than it first appears and sometimes higher than renting an equivalent property privately.
Key things to check before proceeding:
Service charges and their escalation. Service charges often increase annually and are not capped in the way rent on the unsold share is. A £ 150-per-month service charge today may be £250 in five years.
Lease length. Shared ownership properties are leasehold. Check the remaining lease length – lenders typically require at least 70 years remaining, and a short lease is expensive to extend.
Staircasing costs. Each time you buy an additional share, you pay for a new valuation and legal fees. If property values have risen, the additional shares cost more than the original purchase price.
Resale restrictions. When you sell, the housing association typically has a period of first refusal to find another buyer, which can slow the sale process.
Frequently asked questions
Who is eligible for shared ownership? Shared ownership is available to first-time buyers and to people who previously owned a home but cannot currently afford to buy. There are income caps – typically £80,000 outside London and £90,000 in London – though these vary by scheme. The property must be your only home.
Can I rent out a shared ownership property? Generally, no-shared ownership properties must be your primary residence and cannot be sublet without the housing association’s permission, which is rarely granted.
What happens when I staircase to 100%? When you own 100% of the property, the rent stops, your lease converts to a freehold (in most cases), and you have the same ownership rights as any other homeowner. The mortgage at that point covers the full property value.
Is shared ownership worth it? It depends entirely on your local market, the specific property and scheme, and the available alternatives. The calculator makes the total monthly cost visible – compare this to equivalent private rents and outright purchase costs before deciding.
Related tools and posts
- Mortgage affordability calculator — what you could borrow for outright purchase
- Stamp duty calculator — stamp duty applies to the share you purchase
- Rent vs buy calculator — compare shared ownership to renting
- What is shared ownership and is it worth it?