This Practice Note discusses the statutory right (subject to statutory qualifying criteria) of a tenant who holds a long lease of a flat to buy a 90-year extension of the lease under the Leasehold Reform, Housing and Urban Development Act 1993 (LRHUDA 1993), including guidance in respect of valuation and calculation of premium, procedure including service of a section 42 notice and section 45 counter-notice, treatment of intermediate landlords, registration, assignment, deposit, failure to comply, terms of the new lease, First-tier Tribunal (or Leasehold Valuation Tribunal in Wales) and County Court procedure, payment of premium, completion, and withdrawal of claim.