Renters' Rights Act 2025, Phase 1 commencement
Transition readiness pack

Development & Land

Site Assembly UK — Option Agreements, Promotion Agreements, Ransom Strips, and Overage Clauses

Covers option agreements (option fee; GDV formula; minimum price floor; TotE issues); promotion agreements (promoter's fee of 15-30%; open market sale; alignment of incentives; tax advantage); ransom strips (Stokes v Cambridge one-third formula; negotiating services rights; Access to Neighbouring Land Act 1992); and overage clauses (trigger events; formula; duration; HMLR registration; CGT vs income tax treatment).

17 min readUpdated 8 June 2026Last reviewed: 17 May 2026site-assemblyoption-agreementpromotion-agreementransom-strip

Option Agreements and Promotion Agreements

Option agreement: developer pays an option fee for the right (not obligation) to purchase land at a formula price once planning permission is obtained; typical option period 2-5 years; price expressed as GDV × landowner's percentage (typically 15-35%) less infrastructure costs; key negotiation points — option fee (non-refundable); minimum price floor; limited option period with renewal fees; developer diligence obligations; valuation dispute mechanism (RICS expert determination). Promotion agreement: promoter obtains planning at their own cost; land sold on the open market; promoter takes 15-30% of net proceeds as fee; landowner retains ownership throughout; open market sale delivers competitive bidding — typically higher than bilateral option formula. Key advantages for landowners: aligned promoter incentive (higher sale price = higher fee); landowner retains use of land during planning process; no lock-in to a single buyer. Key risk: landowner cannot refuse a satisfactory planning permission once it is granted.

Ransom Strips — Value and Negotiation

A ransom strip is a small piece of land that controls access or services to a larger development site. Ransom value: based on the additional development value the access creates — the Stokes v Cambridge (1961) formula of one-third of the development value is the historical starting point; modern practice produces 33-50% of the uplift depending on alternative access availability. Negotiate services rights separately from access rights — the developer will need to lay drainage, electricity, gas, water, and broadband through the strip; charge for each right. Access to Neighbouring Land Act 1992: a developer may apply to court for access to carry out works — the ransom strip owner receives compensation but loses control of timing. CPO: planning authorities can compulsorily acquire ransom strips in limited circumstances. Practical steps: obtain a RICS valuation; instruct a specialist solicitor; do not accept the developer's first offer; ensure the agreement addresses future development phases (not just the current scheme).

Overage Clauses — Capturing Future Development Value

Overage (clawback/uplift): contractual right for the original landowner to receive additional payments if the land obtains planning permission or increases in value after sale. Trigger events: planning permission grant; commencement of development; sale to a third party. Formula: (value with planning − base value) × landowner's percentage (typically 20-50%). Duration: commonly 10-25 years. Security: register an overage restriction or charge at HMLR immediately on completion — without registration, the obligation may not bind a subsequent purchaser of the title. Tax: overage is generally CGT (not income tax) as deferred sale consideration — but HMRC may challenge income treatment for trading landowners; specialist tax advice essential. Practical: negotiate the formula, the base value, the landowner's percentage, and the duration with equal care to the primary sale price.

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