Staircasing Stamp Duty: Additional Share Purchases

What Is Staircasing?

Staircasing is the process of buying additional equity in your shared ownership property from the housing association. When you initially bought your share (say 40%), the lease granted you the right to purchase more shares over time. Each time you buy an additional percentage, you are staircasing. You can staircase as many times as you like (subject to your lease terms) until you reach 100% ownership.

The price you pay for each additional share is based on the current open market value of the property at the time of that specific staircasing transaction. If your property has increased in value since you first bought, you will pay more per percentage point than you did initially. This is why property value growth affects the total SDLT liability under the staircasing election.

For context on how your initial election affects whether you pay SDLT at all on staircasing, see the market value election guide. If you made the market value election at your initial purchase, you pay no SDLT on any staircasing transaction, full stop. The rules on this page apply where you did not make the market value election, ie. you are using the default pay-in-stages option.

When SDLT Applies on Staircasing

Under the default pay-in-stages option, HMRC sets a very specific rule for further SDLT obligations on staircasing tranches. Per GOV.UK guidance: “If you buy more shares in a property... until your share reaches more than 80%, you don't pay any more SDLT or tell HMRC about the transactions in a SDLT return.”

In other words, there is no further SDLT and no SDLT return required while your total ownership remains at 80% or below, no matter how large each staircasing tranche is. The SDLT system only re-engages when a transaction takes your cumulative ownership over 80%.

Staircasing Below and Up To 80%

While your total ownership stays at 80% or below after a staircasing tranche, no SDLT is due and no SDLT return is required for that transaction. This is a feature of the shared ownership SDLT regime, not a function of the rate bands: even if you bought a single tranche worth £400,000, you would still owe nothing at that point, because you have not yet crossed the 80% line.

The price you pay for each tranche is still based on a current RICS valuation of the whole property. The housing association calculates the share price as a percentage of that valuation. That price affects how much you pay, but it does not create a current SDLT liability until the 80% line is crossed.

Note that first-time buyer relief does not apply to staircasing purchases in any case. Under the pay-in-stages option the relief covers only the first transaction, the grant of your lease (HMRC manual SDLTM29885). When SDLT does eventually become payable on an 80% crossing, standard rates apply.

Crossing the 80% Threshold

The 80% line is the trigger point for SDLT on staircasing under the pay-in-stages option. The specific rule, set out in FA 2003 Schedule 9 and explained in the HMRC guidance, is that the grant of your lease and all staircasing transactions are linked transactions for SDLT (HMRC manual SDLTM27065). For the transaction that takes you over 80%, you work out the SDLT on the total you have paid for the property so far, including the premium for your initial share, and then apportion it. The crossing transaction bears the fraction of that tax that its own price bears to the total.

Two things are never taxed again. If your lease was granted on or after 12 March 2008, the initial share premium is not recharged at a higher rate, and tranches that kept you at or below 80% are not brought back into charge. They still count towards the total that sets the rate.

Critically, this is not a market value calculation. The SDLT is based on the consideration actually paid, not on the current open market value of the whole property. The market value basis applies only where the market value election was made at the first purchase, in which case no further SDLT arises at all.

Linked Transactions Rule After 80%

Once the 80% line has been crossed, any further staircasing is also captured by the linked transactions rule. For each later purchase, the SDLT is worked out on the new total paid for the property and apportioned in the same way. The new tranche bears its own share of that tax.

Because the total has grown, the earlier tranche that took you over 80% now carries a larger apportioned share too. You pay the difference on that earlier transaction and tell HMRC with a further return under section 81A of the Finance Act 2003. GOV.UK's own worked examples on the shared ownership guidance page show exactly this top-up.

Each of these further staircasing transactions requires a new SDLT return within 14 days of the effective date. Before 80% is crossed, no returns are required at all. After 80% has been crossed, every staircasing tranche is a notifiable, linked transaction.

Example: Staircasing Below 80%

Example: Crossing 80% in One Transaction

Example: Further Staircasing After 80%

Filing Requirements

The filing position for staircasing under the pay-in-stages option is unusually simple. While your cumulative ownership stays at 80% or below, no SDLT return is required for staircasing transactions, no matter how large each tranche is. HMRC guidance is explicit on this point.

A return becomes required for the transaction that takes your cumulative ownership over 80%, and for every subsequent staircasing transaction (which are all linked). Each such return must be filed within 14 days of the effective date, normally completion day. Any SDLT due must accompany the return.

Your solicitor handles the SDLT return for any notifiable staircasing transaction. The Land Registry requires evidence of the SDLT filing (a SDLT certificate) before registering the updated ownership title where a return was due. Where no return is required (staircasing up to 80%), the Land Registry update proceeds on the basis of the staircasing memorandum alone.

Strategic Planning to Manage Staircasing SDLT

Under the pay-in-stages option, the shape of the 80% rule drives most planning decisions. Several strategies are worth considering:

Stop at 80% if possible: If your long-term plan is to own around 80% and no more, you will never pay any further SDLT beyond your initial share premium. Every tranche up to 80% is free of SDLT and free of any return obligation.

Go straight from below 80% to 100%: If you intend full ownership, one way to minimise SDLT complexity is to stay at or below 80% and then make a single transaction to 100%. That single transaction is the only one above 80%, so there is one SDLT calculation, one return and no later top-ups.

Understand the linked transactions rule before crossing 80%: Even a small tranche that crosses 80% takes its rate from the total you have paid for the property, including your initial share, so the rate can be higher than the tranche price alone suggests. Make sure you model this before staircasing. See the final staircasing guide for how the final step to 100% fits in.

Moving to Final Staircasing

When you are ready to buy the final share and reach 100% ownership, different considerations apply. The final staircasing to 100% guide covers the SDLT calculation on that last purchase, the transition from leasehold to potential freehold, and mortgage and legal considerations specific to becoming a full owner.

For context on how the shared ownership journey fits together from start to finish, the shared ownership complete guide provides an overview of all SDLT touchpoints across the entire lifecycle.

Run the Numbers on Your Staircasing Purchase

Once you understand the 80% threshold and linked-transaction rules above, the next step is the actual SDLT figure. The staircasing calculator handles both phases, tranches that stay at or below 80% (zero further SDLT) and the linked-transaction computation when you cross the line, and lets you stress-test sequences of future tranches before you commit.

Frequently Asked Questions