The Ministry of Housing, Communities and Local Government has quietly detonated a compliance time bomb under the private rented sector. Updated guidance on the Tenant Fees Act now suggests that professional rent guarantor contracts signed before the Renters' Rights Act came into force on 1 May 2025 may be legally unenforceable, or at the very least open to challenge. For an industry that has leaned heavily on guarantor schemes to underwrite riskier tenancies - students, first-jobbers, migrants without UK credit histories - this is not a technical footnote. It is a structural crack in one of the sector's most widely used risk-mitigation tools.