It's rarely the licence a landlord forgot about that catches them out — it's a certificate that quietly expired.
Five real, recurring obligations, plainly stated: Gas Safety Certificate (annual, unlimited fine/imprisonment risk if missing and gas is present), EICR — electrical safety (every 5 years, up to £30,000 civil penalty), EPC — energy performance (every 10 years, must be E or above to let legally, up to £5,000 penalty), tenancy deposit protection (30 days from taking it, invalidates possession routes if missed), and smoke/CO alarm compliance (up to £5,000 per breach, checked at every tenancy start).
None of these are one-time — they lapse on a schedule, and a landlord juggling more than one property is the most likely to lose track of which certificate covers which address.
Free check tells you exactly which of these you're currently missing for one property, dated and sourced.
Check my compliance — free Browse your council's page