When your landlord cites a mandatory ground in a Section 8 notice, the stakes are higher because the court has no discretion. If the landlord proves the ground applies, the court must grant the possession order, regardless of your personal circumstances. The court can't consider whether it's "reasonable" to evict you or take into account factors like children in the household, health issues, or difficulty finding alternative accommodation.
The key mandatory grounds under the reformed Section 8 (post-Renters' Rights Act) are:
Several mandatory grounds come with restrictions. Grounds 1 and 1A, for example, can't be used within the first 12 months of the tenancy, and they require four months' notice, while Ground 8 now excludes arrears that have built up solely because universal credit payments haven't yet been received.
Because the court must grant possession on mandatory grounds, your main defence is challenging whether the ground is genuinely made out. If the landlord says they intend to sell but you have evidence suggesting otherwise, you can argue the ground isn't proven.