Shared Ownership Staircasing Calculator

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. Most shared owners start with a 25-75% share, and every staircase shrinks the rent charged on the share the housing association still holds. Suppose you bought a 25% share of a £300k flat for £75k and pay rent on the other 75%, roughly £10k a year. Staircase to 50% and that rent halves to about £5k a year.

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, with mortgage fees of £999-£1,500 if you remortgage and lender legal fees of £150-£300 on top. If you staircase to 100%, you become a full owner and no longer pay rent to the housing association. The revaluation often shows growth, which means the price of each percentage point rises while you are still staircasing. If that £300k flat is now worth £350k, moving from 25% to 50% costs £87,500 plus £1,500-£2,500 in fees, rather than the £75k the same share cost originally.

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 set against a higher mortgage payment) and the break-even period, meaning how long the rent saving takes to pay back what you spent on fees and extra borrowing.

Stamp duty may be payable on the cumulative shares purchased once the total exceeds the nil-rate threshold, and the position depends on the election made at the original purchase. Buyers could either pay SDLT in full upfront or pay only on the share purchased and the rent, settling the rest later. Most pay in full upfront, which tends to work out better over the long term. If you chose to defer, SDLT becomes due when your total share exceeds 80%, and it is charged on the current market value of the property. Someone who bought a 25% share for £75k and paid SDLT only on that £75k, then staircases to 90%, owes SDLT on the extra 65% at today's price. The bill can be substantial, so professional advice before a final staircase is money well spent.

Staircasing to 100% makes sense if you can afford the full mortgage, the property has appreciated and you plan to stay long-term. It makes less sense if you expect to move within 3-5 years, if the rent on the shared portion is below what the equivalent mortgage would cost, or if the remaining mortgage would stretch your budget. Most shared owners who can afford it staircase to 100% within 5-10 years, while some keep shared ownership permanently for its lower monthly outgoings and predictable costs.

Compared with selling and buying elsewhere, staircasing keeps your property while increasing your ownership, avoids moving costs, carries lower commission than a full sale and preserves the EPC rating and any improvements you have made. The drawbacks are limited choice, since you are committed to the current property, and the risk that a revaluation comes in high so you pay more. Selling gives full open market access but means SDLT on the new property and estate agent fees of £3-£8k on the sale. Staircasing is typically cheaper than selling and buying by £3-£8k unless you would benefit from changing location.