Guide to SDLT Calculation for Leases with Variable or Uncertain Rent

SDLT and lease rent reviews: calculating NPV where rent is uncertain

When working out SDLT on a new lease, the rent is converted into a net present value (NPV). If the lease includes a rent review, the key point is whether that review takes effect within the first five years of the term or later. A review within the first five years means you must use a reasonable estimate of the rent for that period. A review after the first five years is generally ignored for NPV purposes, with later rent dealt with under the separate rule for variable rent after year five.

• If rent is fixed from the start, the NPV calculation is usually straightforward; rent reviews make the rent variable or uncertain.
• Where a rent review falls within the first five years, the rent is treated as uncertain at the grant date and a reasonable estimate must be used.
• HMRC does not always require a professional valuation, but you should keep evidence showing how your estimate was reached.
• If the first review is after year five, the review itself is ignored in the NPV calculation and the later period is dealt with under the separate variable-rent rule.
• The same general treatment applies to statutory rent reviews for agricultural tenancies, and special borderline rules can apply where a review falls just within the first five years.

Scroll down for the full analysis.

SDLT on lease rent reviews: how to calculate NPV when rent is variable or uncertain

This page explains how SDLT deals with lease rent where the lease includes a rent review. The main issue is whether the rent review happens within the first five years of the term or later. That timing affects how you calculate the net present value, or NPV, of the rent for SDLT purposes.

What this rule is about

SDLT on the grant of a lease can be charged by reference to the rent payable over the term. To work that out, the rent is converted into an NPV figure. That calculation is straightforward where the rent is fixed from the start. It becomes more difficult where the lease says the rent may change, because the amount payable is not fully known on the grant date.

A rent review makes the rent variable or uncertain. The legislation and HMRC guidance set out special rules for dealing with that uncertainty. The key distinction is whether the review happens in the first five years of the lease term or after that period.

What the official source says

HMRC’s manual says that if the lease provides for a rent review within the first five years, the rent is variable and uncertain at the date of grant. In that situation, for the first five years you should use a reasonable estimate of the rent payable when calculating NPV. HMRC refers to Finance Act 2003, section 51(2).

HMRC also says that this estimate does not have to come from a professional valuation. But you should keep evidence showing how you arrived at the estimate, in case HMRC asks about it later.

If the rent review falls after the end of the fifth year, HMRC says the review is ignored when calculating NPV for SDLT. Even so, because the rent is variable, the NPV for the period after the first five years is taken using the highest rent rule referred to in HMRC’s related guidance.

The same approach applies to statutory rent reviews under the legislation for agricultural tenancies.

The manual also notes that there are special rules for a review that falls just within the first five years. In some cases, a review technically within that period is treated as if it fell after the fifth year. HMRC deals with that separately.

What this means in practice

The practical question is not simply whether there is a rent review. It is when the review takes effect.

If the review is within the first five years, you cannot just ignore it. You must make a reasonable estimate of the rent that will be payable during that period and use that estimate in the NPV calculation.

If the review is after the first five years, you do not try to predict the reviewed rent for SDLT purposes. Instead, the review is disregarded in the NPV calculation, and the later years are dealt with under the separate rule for variable rent after year five.

This matters because the SDLT return is made at the start of the lease, when the future reviewed rent may not yet be known. The rules are designed to give a workable method for filing the return without waiting for the review to happen.

It also means record-keeping is important. Where an estimate is required, HMRC expects the tenant or adviser to be able to show the basis used. The source material does not insist on a formal valuation in every case, but it does expect a rational and evidenced estimate.

How to analyse it

A sensible way to approach the issue is:

• Identify whether the lease contains a rent review mechanism at all.
• Work out exactly when the review falls under the lease terms.
• Ask whether that date is within the first five years of the term, after the first five years, or in a borderline position covered by HMRC’s separate guidance.
• If the review is within the first five years, make a reasonable estimate of the rent payable for that period and keep evidence of how you reached it.
• If the review is after the first five years, disregard the review itself for NPV purposes and apply the rule for variable rent after year five.
• If the tenancy is an agricultural tenancy with a statutory review mechanism, remember that HMRC says the same treatment applies.

When making an estimate, the source material does not prescribe a single method. The important point is reasonableness and evidence. The estimate should be based on something that can be explained if queried.

Example

Illustration: a tenant takes a 10-year lease. The lease says the rent will be reviewed in year 3. Because the review falls within the first five years, the rent is treated as variable and uncertain from the start. The NPV calculation for the first five years should therefore use a reasonable estimate of the rent payable after that review, and the basis for that estimate should be kept on file.

By contrast, if the same lease provided for the first review in year 6, that review would be disregarded for the NPV calculation. The post-five-year period would instead be dealt with under the rule for variable rent after year five.

Why this can be difficult in practice

The main difficulty is often timing. Lease drafting may make it unclear exactly when a review takes effect, especially where there are review dates, implementation dates, or machinery that delays the final figure. HMRC’s manual itself recognises that a review just within the first five years may sometimes be treated differently.

Another difficulty is deciding what counts as a reasonable estimate. The source material says a professional valuation is not always needed, but it does not give a detailed formula. That leaves room for judgment. An estimate should not be arbitrary, and it should be supported by material that shows why it was reasonable at the effective date of the transaction.

A further point is that the manual is explaining HMRC’s approach, not rewriting the legislation. Where the lease terms are unusual, the legal analysis still turns on the statutory rules and the actual drafting of the lease.

Key takeaways

• A rent review within the first five years means the rent is variable and uncertain at grant, so a reasonable estimate is needed for the NPV calculation.
• A rent review after the first five years is disregarded for NPV purposes, with later years dealt with under the separate variable-rent rule.
• You do not always need a professional valuation, but you should keep clear evidence showing how any estimate was reached.

This page was last updated on 24 March 2026

Useful article? You may find it helpful to read the original guidance here: Guide to SDLT Calculation for Leases with Variable or Uncertain Rent

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