Anchored to UK statute. Last verified 21 June 2026. View source-of-record.

maduediligencechecklist.co.uk

The UK M&A Due Diligence Checklist

Typical plan

UK diligence timeline - 4 to 6 weeks


A typical UK lower-mid-market deal moves from signed LOI to exchange in 4-6 weeks. The critical path tends to be tax-deed scope and regulatory clearance, not the data-room itself. NSI, FCA and CMA clocks can extend completion materially.

Direct answer

A UK lower-mid-market diligence timeline runs 4-6 weeks from LOI to exchange. FCA change-of-control adds a 60 working-day decision clock. NSI Act mandatory notification adds a 30 working-day acceptance period before the call-in window. CMA Phase 1 review takes 40 working days from notification. Plan completion 0-30 days after exchange.


  1. Week 0

    LOI / heads of terms signed

    • - LOI / heads signed.
    • - Exclusivity window agreed.
    • - Adviser engagements scoped, data room access provisioned.
  2. Week 1

    Open data room, first-pass

    • - FDD partner reads management accounts.
    • - Legal partner reads CA / PSC / register pack.
    • - Tax partner reads CT computations.
    • - First Q&A list issued.
  3. Week 2

    Deep-dive workstreams

    • - Q&A turn from seller.
    • - FDD QoE adjustments drafted.
    • - Commercial DD interviews booked.
    • - IT / cyber report kicked off.
    • - Phase I ESA commissioned if relevant.
  4. Week 3

    Findings consolidate

    • - Draft FDD report circulated.
    • - Tax-deed scope drafted.
    • - Customer reference calls.
    • - Regulatory check (NSI, CMA, FCA) confirmed.
  5. Week 4

    Reports finalised

    • - Final FDD, tax DD and legal DD reports.
    • - Disclosure letter first draft.
    • - W&I underwriter market sounded if relevant.
  6. Week 5-6

    Negotiation and exchange

    • - SPA negotiated.
    • - Disclosure letter agreed.
    • - Conditions precedent signed off.
    • - Exchange.
    • - Completion typically 0-30 days after exchange.

Where the timeline slips

  • NSI Act mandatory notification. 30 working-day acceptance period before a call-in window; 30 working-day review can extend by 45.
  • FCA change-of-control. 60 working-day determination period from a complete application.
  • CMA Phase 1. 40 working days; Phase 2 adds 24 weeks if the deal is referred.
  • Pension scheme clearance. 3 months from a TPR clearance application if a DB scheme is in scope.
  • Tax-deed negotiation. Often the longest single negotiation strand; budget two weeks of partner time.

Reviewed by Oliver Wakefield-Smith, Founder, Digital SignetLast verified 21 June 2026

This page is anchored to UK primary legislation and named regulator guidance only. Not legal advice. Confirm position with your appointed adviser before signing.