The Property Filter Lease Extension Calculator

The Property Filter Lease Extension Calculator

The Property Filter Lease Extension Calculator

A clear, investor-friendly way to estimate the lease extension premium for a leasehold flat or house in England & Wales. This page explains what the calculator does, how to use it, and how the maths works—in plain English.

A clear, investor-friendly way to estimate the lease extension premium for a leasehold flat or house in England & Wales. This page explains what the calculator does, how to use it, and how the maths works—in plain English.

A clear, investor-friendly way to estimate the lease extension premium for a leasehold flat or house in England & Wales. This page explains what the calculator does, how to use it, and how the maths works—in plain English.

Lease Extension Calculator

How to Use:

How to Use:

How to Use:

Enter years left

Enter years left

Enter years left

Input the years remaining on your lease (whole years are fine—no months needed).

Current ground rent

Current ground rent

Current ground rent

Enter your annual ground rent (£/pa).

Property value

Property value

Property value

Enter the likely property value once extended by 90 years (peppercorn rent)

Calculate

Calculate

Calculate

Click to see the premium range and a full breakdown.

Results Explained

Results Explained

Ground-rent loss (freeholder’s lost income)

Ground-rent loss (freeholder’s lost income)

Ground-rent loss (freeholder’s lost income)

When you extend, the ground rent becomes a peppercorn (effectively £0). The freeholder loses that income for the rest of the existing term. We capitalise that stream of rent using a standard years-purchase factor (a time-value-of-money calculation).

When you extend, the ground rent becomes a peppercorn (effectively £0). The freeholder loses that income for the rest of the existing term. We capitalise that stream of rent using a standard years-purchase factor (a time-value-of-money calculation).

Reversionary interest (waiting longer for the asset back)

Reversionary interest (waiting longer for the asset back)

Reversionary interest (waiting longer for the asset back)

Without extension, the freeholder regains the property’s full value when the lease expires. With extension, they must wait an extra 90 years. We discount the property’s value back to the present at the end of:

  • the current term; and

  • the current term + 90 years, and take the difference.

Without extension, the freeholder regains the property’s full value when the lease expires. With extension, they must wait an extra 90 years. We discount the property’s value back to the present at the end of:

  • the current term; and

  • the current term + 90 years, and take the difference.

Marriage value (only if < 80 years left)

Marriage value (only if < 80 years left)

Marriage value (only if < 80 years left)

Extending a short lease usually makes the flat worth more than the sum of its parts today (tenant’s short lease + freeholder’s reversion). That uplift is called marriage value and, under current rules, the leaseholder typically pays 50% of that uplift.

If the lease is 80+ years, marriage value is not charged.

Extending a short lease usually makes the flat worth more than the sum of its parts today (tenant’s short lease + freeholder’s reversion). That uplift is called marriage value and, under current rules, the leaseholder typically pays 50% of that uplift.

If the lease is 80+ years, marriage value is not charged.

Inputs & Assumptions

Inputs & Assumptions

Years left on lease – Whole years (we ignore months to keep data entry simple).

Years left on lease (T) – Whole years (we ignore months to keep data entry simple).

Ground rent – £ per annum.

Ground rent (G) – £ per annum.

Property value once extended – Market value with a +90-year extension at a peppercorn rent.

Property value once extended (V) – Market value with a +90-year extension at a peppercorn rent.

Ground rent capitalisation – Uses 6% years-purchase factor for capitalising lost ground rent.

Ground rent capitalisation – Uses 6% years-purchase factor for capitalising lost ground rent.

Reversionary interest – Uses 5% deferment rate for calculating present values.

Reversionary interest – Uses 5% deferment rate for calculating present values.

Relativity for marriage value – Applied within marriage-value calculation for short lease valuation.

Relativity for marriage value – Applied within marriage-value calculation for short lease valuation.

Estimate band – We present ±3% around the computed average to give a sensible low–high range

Estimate band – We present ±3% around the computed average to give a sensible low–high range

These are standard, widely used parameters for educational calculators. Professionals may use different rates/relativities depending on market evidence, tribunal precedents, and the particulars of your lease.

These are standard, widely used parameters for educational calculators. Professionals may use different rates/relativities depending on market evidence, tribunal precedents, and the particulars of your lease.

Reading Your Results (Example Logic)

Reading Your Results (Example Logic)

Estimated Premium Range – The average premium ±3% to give a realistic band.

Estimated Premium Range – The average premium ±3% to give a realistic band.

Ground-Rent Loss – Shows your ground rent, the years-purchase factor, and the capitalised loss.

Ground-Rent Loss – Shows your ground rent, the years-purchase factor, and the capitalised loss.

Reversionary interest – Shows the discounted value at T years and at T+90 years, and the difference.

Reversionary interest – Shows the discounted value at T years and at T+90 years, and the difference.

Marriage Value (if <80 years) – Shows current vs future combined interests and the 50% share payable.

Marriage Value (if <80 years) – Shows current vs future combined interests and the 50% share payable.

When you should speak to a professional

When you should speak to a professional

Unusual or escalating ground-rent clauses (e.g., doubling, RPI uplifts).

Very short leases (where small changes in assumptions swing the numbers).

A big gap between your estimate and the freeholder’s figure.

You’re planning to negotiate, challenge, or prepare for tribunal.

A valuer brings comparable evidence and expert judgement; a solicitor ensures the process and terms protect your position.

Frequently Asked Questions

Frequently Asked Questions

Is this calculator's estimate exact?

Is this calculator's estimate exact?

Is this calculator's estimate exact?

Is this calculator's estimate exact?

Why does the number jump at 80 years?

Why does the number jump at 80 years?

Why does the number jump at 80 years?

Why does the number jump at 80 years?

What should I use for “value once extended”?

What should I use for “value once extended”?

What should I use for “value once extended”?

What should I use for “value once extended”?

How long is the lease after extension?

How long is the lease after extension?

How long is the lease after extension?

How long is the lease after extension?

Can I just pay the calculator’s figure?

Can I just pay the calculator’s figure?

Can I just pay the calculator’s figure?

Can I just pay the calculator’s figure?

When should I speak to a professional?

When should I speak to a professional?

When should I speak to a professional?

When should I speak to a professional?

Ready to find Short Lease Deals?

Ready to find Short Lease Deals?

Ready to find Short Lease Deals?

Ready to find Short Lease Deals?

Appendix: The Maths

Appendix: The Maths

Below is a compact, self-contained presentation of the textbook calculation that underpins our breakdown. Symbols:

Below is a compact, self-contained presentation of the textbook calculation that underpins our breakdown. Symbols:

G – Annual ground rent (£)

T – Years left on the current lease

v – Current market value with the short lease (£)

V – Market value once extended by 90 years at peppercorn rent (£)

ε – Yield/discount rate (6% for ground rent, 5% for reversion)

Ground-rent loss (capitalised)

Ground-rent loss (capitalised)

Years-purchase factor:

Ground-rent loss:

Where ε_GR = 6% in the calculator

Reversionary interest (deferred value difference)

Reversionary interest (deferred value difference)

Present value of the reversion at the end of the current term and the extended term:

Present value of the reversion at the end of the current term and the extended term:

Where ε_DEF = 5% in the calculator

Diminution of the freeholder’s interest

Diminution of the freeholder’s interest

Marriage value (only if T<80T < 80)

Marriage value (only if T<80T < 80)

Intuition: the long-lease flat is usually worth more than (short-lease tenant’s value + freeholder’s reversion today). The uplift is the marriage value; the leaseholder typically pays 50% of that uplift.

A common practical way to express the uplift is to compare combined interests now versus combined interests after extension:


  • Current combined = (tenant’s short-lease value) ++ (freeholder’s reversion now)

  • Future combined = (tenant’s long-lease value =V=V) ++ (freeholder’s reversion after +90 years)


The difference (if positive) is the marriage uplift; the amount payable is 50% of that:

Intuition: the long-lease flat is usually worth more than (short-lease tenant’s value + freeholder’s reversion today). The uplift is the marriage value; the leaseholder typically pays 50% of that uplift.

A common practical way to express the uplift is to compare combined interests now versus combined interests after extension:


  • Current combined = (tenant’s short-lease value) ++ (freeholder’s reversion now)

  • Future combined = (tenant’s long-lease value =V=V) ++ (freeholder’s reversion after +90 years)


The difference (if positive) is the marriage uplift; the amount payable is 50% of that:

In practice, valuers often express the tenant’s current value vv via a relativity to VV (e.g., v=Relativity×Vv = \text{Relativity}\times V) based on market/tribunal evidence for the specific term.

In practice, valuers often express the tenant’s current value vv via a relativity to VV (e.g., v=Relativity×Vv = \text{Relativity}\times V) based on market/tribunal evidence for the specific term.

Total premium

Displayed estimate

Average = the premium from the steps above

Average = the premium from the steps above

Range = Average × 0.97 (low) and Average × 1.03 (high).

Range = Average × 0.97 (low) and Average × 1.03 (high).

How Long is the Lease After You Pay the Premium?

How Long is the Lease After You Pay the Premium?

Quick Answer

Flats (statutory): Your new term is your current unexpired term + 90 years. Ground rent becomes peppercorn (£0) for the whole new term.


Houses (statutory): You get an extra 50 years added from the current lease end. You don't pay a premium for this statutory extension, but the lease switches to a "modern ground rent" during the additional term, which is usually higher than the old ground rent.

This page summarises the standard statutory position in England & Wales. Informal (negotiated) deals can be different—see below.

Flats (statutory route) — what you actually get

Your existing lease is replaced with a new lease that runs for 90 years longer than whatever you have left today.

Your existing lease is replaced with a new lease that runs for 90 years longer than whatever you have left today.

Your existing lease is replaced with a new lease that runs for 90 years longer than whatever you have left today.

Ground rent is reduced to peppercorn (£0) for the entire new term.

Ground rent is reduced to peppercorn (£0) for the entire new term.

You pay a premium (the calculator estimates this) plus the freeholder's reasonable legal/valuation costs.

You pay a premium (the calculator estimates this) plus the freeholder's reasonable legal/valuation costs.

You pay a premium (the calculator estimates this) plus the freeholder's reasonable legal/valuation costs.

The length of your current term doesn't affect the +90 rule; it's always current years remaining plus ninety.

The length of your current term doesn't affect the +90 rule; it's always current years remaining plus ninety.

The length of your current term doesn't affect the +90 rule; it's always current years remaining plus ninety.

Example: If you have 67 years left today: your new lease = 67 + 90 = 157 years, and ground rent becomes £0 for all 157 years.

Houses (statutory route) — how it differs

You receive a 50-year extension measured from the end of your current lease (the expiry date moves out by 50 years).

You receive a 50-year extension measured from the end of your current lease (the expiry date moves out by 50 years).

You receive a 50-year extension measured from the end of your current lease (the expiry date moves out by 50 years).

There is no premium charged for this statutory extension of a house, but:

There is no premium charged for this statutory extension of a house, but:

the rent during the additional 50-year period becomes a "modern ground rent", assessed by formula and usually higher than your old rent;

the rent during the additional 50-year period becomes a "modern ground rent", assessed by formula and usually higher than your old rent;

the rent during the additional 50-year period becomes a "modern ground rent", assessed by formula and usually higher than your old rent;

the rent during the additional 50-year period becomes a "modern ground rent", assessed by formula and usually higher than your old rent;

you still pay the freeholder's reasonable legal/valuation costs.

you still pay the freeholder's reasonable legal/valuation costs.

you still pay the freeholder's reasonable legal/valuation costs.

Example: If you have 45 years left today: your new lease end becomes 45 + 50 = 95 years from today. During the extra 50 years, you pay modern ground rent instead of your old ground-rent terms.

Why is the rule different for houses? Houses are covered by a different piece of legislation. The policy intent is that you can either extend by 50 years (with modern ground rent) or buy the freehold (enfranchise). Many owners compare both routes.

Informal extensions (negotiated, "outside the Act")

You and the freeholder can agree any term length (e.g., +125 years, +250 years).

You and the freeholder can agree any term length (e.g., +125 years, +250 years).

Ground rent terms are whatever you negotiate (they may stay, rise, or be set to peppercorn)

Ground rent terms are whatever you negotiate (they may stay, rise, or be set to peppercorn)

Caution: Watch out for escalating ground-rent clauses (doubling, index-linked) that can affect value and mortgageability. If you need a clean outcome, state peppercorn ground rent in the new lease.

Recent changes & what's next (as of 9 August 2025)

The two-year ownership rule for statutory claims was removed on 31 January 2025. You no longer need to wait two years after purchase to start a statutory lease extension or enfranchisement claim.

Parliament has legislated for longer standard extensions (up to 990 years) and other reforms, but several provisions require commencement/secondary legislation before they apply. Until commenced, the rules above (+90 for flats, +50 for houses) are the ones you use today.

Quick FAQs

Does marriage value affect the number of years?

No. Marriage value affects the price, not the length. Length is fixed by statute: +90 (flats) or +50 (houses).

No. Marriage value affects the price, not the length. Length is fixed by statute: +90 (flats) or +50 (houses).

No. Marriage value affects the price, not the length. Length is fixed by statute: +90 (flats) or +50 (houses).

Will an extension always set ground rent to £0?

Flats (statutory): yes, peppercorn (£0) for the whole new term.
Houses (statutory): no premium, but modern ground rent applies during the additional 50 years.
Informal: whatever you negotiate (aim for peppercorn if you want a clean outcome).

Flats (statutory): yes, peppercorn (£0) for the whole new term.
Houses (statutory): no premium, but modern ground rent applies during the additional 50 years.
Informal: whatever you negotiate (aim for peppercorn if you want a clean outcome).

Flats (statutory): yes, peppercorn (£0) for the whole new term.
Houses (statutory): no premium, but modern ground rent applies during the additional 50 years.
Informal: whatever you negotiate (aim for peppercorn if you want a clean outcome).

What if I’m in Scotland or Northern Ireland?

This page covers England & Wales. Scotland and Northern Ireland have different systems.

This page covers England & Wales. Scotland and Northern Ireland have different systems.

This page covers England & Wales. Scotland and Northern Ireland have different systems.

TL;DR

Flats: Current term + 90 years, £0 ground rent.

Houses: +50 years from the current end, modern ground rent for the extra period.

Informal deals: any length/ground-rent you agree—read the fine print.

Disclaimer

Disclaimer

This tool is for education and guidance only. Figures are estimates based on standard assumptions. Actual premiums depend on specific lease terms, valuation evidence, and negotiations. Always seek professional advice from chartered surveyors and specialist solicitors before making decisions.

This tool is for education and guidance only. Figures are estimates based on standard assumptions. Actual premiums depend on specific lease terms, valuation evidence, and negotiations. Always seek professional advice from chartered surveyors and specialist solicitors before making decisions.