Shared Ownership Staircasing Calculator

Calculate the cost of buying a bigger share of your shared ownership home and new rent.

Last updated: April 2026 · Source: GOV.UK — Shared Ownership: staircasing

£

Cost to Buy Extra 25%

£75,000.00

Extra Mortgage

£416.87/mo

Rent Saving

-£171.88/mo

Net Monthly Cost

£245.00

New Rent

£343.75/mo

Staircasing: buy a larger share of your shared ownership home. At 100%, you own it outright and pay no rent. The extra share is valued at current market price, not the original purchase price.

Disclaimer

This calculator is provided for informational purposes only and should not be considered as financial or tax advice. All calculations are performed locally in your browser — no personal data is collected or sent to our servers. Rates and thresholds are sourced from HMRC and GOV.UK and are updated for the current tax year. Always verify results with HMRC or consult a qualified professional before making financial decisions.

How It Works

Staircasing is the process of buying additional shares in a shared ownership property. You can typically buy shares in increments of 10% or more, up to 100% (full ownership). The cost of each additional share is based on the current market value of the property at the time of staircasing, not the original purchase price.

When you staircase, you must pay for an independent RICS valuation (£300-£500), solicitor fees (£500-£1,000) and potentially a new or extended mortgage. If you staircase to 100%, you become a full owner and no longer pay rent to the housing association. Stamp duty may be payable on the cumulative shares purchased once the total exceeds the nil-rate threshold.

This calculator estimates the cost of staircasing from your current share to a target share. Enter the current property value, your current share, target share and mortgage details. It shows the additional purchase cost, the new mortgage amount, the change in monthly costs (reduced rent vs higher mortgage) and the break-even period.

Example: Staircase from 40% to 60% of a £320,000 property

  1. Current share: 40% of £320,000 = £128,000
  2. Additional share: 20% of current value (£320,000) = £64,000
  3. New total share: 60% = £192,000
  4. Rent reduction: from £373/month (60% × 2.75% ÷ 12) to £247 (40% × 2.75% ÷ 12)
  5. Monthly saving on rent: £126 — offset against higher mortgage payment

Source: GOV.UK — Shared Ownership: staircasing

Frequently Asked Questions

What does the Shared Ownership Staircasing Calculator do?
Calculate the cost of buying a bigger share of your shared ownership home and new rent. All calculations are performed in your browser using official UK rates and thresholds.
Is this based on current interest rates?
You can enter any interest rate to model different scenarios. Check the Bank of England base rate and current mortgage deals from lenders for the latest rates.
Should I get professional advice?
This calculator provides estimates for guidance only. For a formal mortgage offer, speak to a mortgage broker or lender who can assess your full circumstances and provide personalised advice.