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Shared ownership deposits explained (UK): how they work and common misunderstandings

Shared ownership deposits are usually based on the share you buy, not the full property value. Learn how it works, with examples and pitfalls.

Published: 03/04/2026 • Last verified: 03/04/2026

Summary

The most common shared ownership deposit misunderstanding is this:

Your deposit is usually based on the share you’re buying, not the home’s full market value.

That can make shared ownership feel more accessible — but it also means you still need to budget for:

  • mortgage fees and legal costs,
  • ongoing rent on the unsold share,
  • and (often) service charges.

Use the shared ownership calculator as you read:

This guide is general information only. Provider rules and lender requirements vary.

Key terms (quick definitions)

  • Share: the percentage you buy with a mortgage and deposit.
  • Unsold share: the part owned by the housing provider; you pay rent on it.
  • Staircasing: buying more shares over time. /glossary/staircasing/
  • Service charge: costs for running/maintaining the building/estate. /glossary/service-charge/

How it works

Step 1: Work out the share price

If the home is valued at £300,000 and you buy a 25% share:

  • Share price: (£300,000 × 0.25 = £75,000)

Step 2: Your deposit is on the share (in many cases)

If you put down a 5% deposit on the share:

  • Deposit: (£75,000 × 0.05 = £3,750)
  • Mortgage on the share: £71,250

Step 3: You still have other costs

Even with a smaller deposit, shared ownership often includes:

  • a reservation fee (up to the provider’s limit),
  • legal fees and searches,
  • lender valuation and mortgage fees (sometimes),
  • rent on the unsold share,
  • and possibly service charges.

Worked examples

These examples are illustrative and simplified.

Example 1: 25% share on a £300,000 home

  • Full value: £300,000
  • Share: 25% → £75,000
  • Deposit: 10% of share → £7,500
  • Mortgage on share: £67,500

Key takeaway: a “10% deposit” here means 10% of £75,000, not 10% of £300,000.

Example 2: 40% share on a £250,000 home

  • Full value: £250,000
  • Share: 40% → £100,000
  • Deposit: 5% of share → £5,000
  • Mortgage on share: £95,000

Key takeaway: larger shares usually mean a larger deposit (because the share price is larger), but they can reduce the rent on the unsold share.

Example 3: “What happens if I staircase later?”

If you increase your ownership share, you typically:

  • pay a new purchase price for the extra shares (based on valuation and rules),
  • reduce the rent (because the unsold share is smaller),
  • may have extra fees (valuation, legal).

Staircasing guide:

Common mistakes

  • Thinking the deposit is on the full value: it’s often based on the share you buy.
  • Forgetting fees and buying costs: reservation, legal, valuation and mortgage fees can apply.
  • Ignoring service charges: these can change over time and affect affordability.
  • Treating the rent as fixed: rent reviews may apply depending on the lease.
  • Assuming staircasing is free: valuation/legal costs can apply.
  • Not stress-testing the total monthly cost: mortgage + rent + service charge should all be budgeted.

What to do next

Related glossary:

Sources