The 80-Year Lease Cliff: Marriage Value, Lender Floors and Onerous Ground Rent in 2026
A leasehold flat gets riskier every year you own it. We break down the 80-year marriage-value cliff, the ~70-year lender floor, and the three "onerous ground rent" tests — including doubling clauses and the £250 AST trap — with the numbers projected to your sale date.
A leasehold flat is the only asset most investors buy that is guaranteed to get riskier every year they own it. The lease term only runs one way, and there are two hard thresholds on the way down: at 80 years remaining, extending the lease suddenly gets much more expensive ("marriage value"); at roughly 70 years, most mainstream lenders walk away and your buyer pool shrinks to cash. Add ground-rent clauses that can make a flat unmortgageable outright, and the cheap flat with the great yield can turn out to be the most expensive thing on your spreadsheet.
The mistake: judging the lease at purchase, not at sale
Conveyancers report the lease term as at completion. But you don't sell at completion — you sell 5, 10, 15 years later, and the buyer's lender tests the term then. Buy with 87 years remaining and hold for 10, and you're marketing a 77-year lease: past the marriage-value cliff, with every viewer's solicitor telling them to price in a lease extension. The threshold questions are always about the term at your exit, not today.
| Lease at purchase | 87 years |
| Planned hold | 10 years |
| Lease at sale | 77 years — crossed the 80-year cliff mid-hold |
| Same deal held 18 years | 69 years — below the ~70-year lender floor |
Threshold 1: the 80-year marriage-value cliff
When a lease with under 80 years remaining is extended, the premium includes marriage value — broadly half of the uplift in the flat's value that the longer lease creates, payable to the freeholder on top of the rest of the premium. Above 80 years, no marriage value is payable at all. That's why 80 is a cliff, not a slope: the cost of the same extension jumps the day the lease ticks under it, and keeps climbing as the term shortens.
The Leasehold and Freehold Reform Act 2024 is set to abolish marriage value — but the valuation provisions have not been commenced, and the timetable (and legal challenges from freeholders) remain unresolved. Until it's actually in force, buyers, lenders and valuers price leases under the current rules. Don't pay 90-year-lease money for a 78-year lease on the assumption the reform lands before you sell.
Threshold 2: the ~70-year lender floor
Most lenders want the unexpired term comfortably above 70 years — commonly expressed as the lease running 30–40 years beyond the end of the mortgage term. A lease that will be under ~70 years while you own it means your eventual buyer either pays cash, uses a specialist lender, or makes their offer conditional on you extending first. All three compress your sale price and your negotiating position.
Threshold 3: onerous ground rent
Ground rent can make a flat hard to mortgage regardless of the lease length. The three red lines lenders and conveyancers apply:
- Rent above ~0.1% of the property value. £300 ground rent on a £280,000 flat is 0.107% — already over the line at many lenders.
- Doubling clauses of every 20 years or less. £300 doubling every 10 years is £600 in year 11, £1,200 in year 21, £2,400 in year 31 — the buyer's conveyancer will project this over their whole mortgage term and many lenders simply refuse.
- Rent above £250 (£1,000 in London). Above these figures the lease can technically qualify as an assured shorthold tenancy — meaning, absurdly, a ground-rent arrears could give the freeholder a mandatory route to possession. Lenders hate it.
The Leasehold Reform (Ground Rent) Act 2022 cut ground rent to a peppercorn on most new long residential leases — but it did nothing for existing leases, which is where all three traps still live.
The quieter leak: service charge compounding
Even a "clean" lease carries a cost line that tends to grow faster than rent. Service charges compounding at 6% against rent growing at 3% shifts the ratio every single year:
| Service charge, year 1 | £2,500 (18% of £13,800 rent) |
| Service charge, year 10 | £4,224 (23% of £18,000 rent) |
| Total carrying cost over 10 years (incl. ground rent + reserve) | £36,000+ |
On a leveraged flat, that drift is frequently the difference between positive and negative cash flow in the back half of the hold — before any major-works bill lands.
How to screen a leasehold deal in five minutes
- Lease years remaining minus your planned hold — is the result under 80? Under 70?
- Ground rent as a % of value, its review clause, and whether it exceeds £250.
- Service charge history (not just this year's figure) and the state of the reserve fund.
- If you're near the cliff: get a lease-extension estimate before you offer, and price it in.
The Leasehold Risk Calculator runs all of this in one pass — it projects service charge and ground rent (including doubling clauses) over your hold, computes the lease term at your sale date, and grades the deal against the 80-year, 70-year and onerous-ground-rent tests. It's a screening tool, not a formal valuation — but it tells you when you need the surveyor.
