The four-month rule
You can apply to renew from four months (and a day) before expiry. Any earlier and the system rejects it. Any later and you're gambling on SIA turnaround times.
Employers with mature compliance teams calendar-block renewals at the six-month mark to give the guard time to complete top-up training.
What top-up training now covers
Emergency First Aid at Work (in-date certificate), the terrorism threat module aligned with Martyn's Law expectations, and a physical intervention refresher for Door Supervisor holders.
Some training providers bundle these; buying separately usually costs more and takes longer.
Handling the gap if you missed the window
You cannot work licensable duties from midnight on your expiry day. Employers who let you work are liable too — expect to be stood down.
The good news: your prior qualification usually still counts, so you only pay for top-ups plus a fresh SIA fee, not a full course.