A single filing calendar for the whole structure
Every company in the structure files on its own clock. Annual returns, tax filings, licence renewals, each with its own date. When no one runs the calendar, deadlines pass quietly and the structure carries the cost later. One calendar keeps every date in front of one set of eyes, and the structure never misses a filing.
One calendar, whole structure
The calendar covers every entity, not the busiest one. Filings, renewals, registrations, and the dates attached to the records all sit on the same list. Nothing lives in a drawer or on a personal device. The office builds the calendar with the people who own the structure, and checks it against the records, so the dates are right and stay right. When a new entity joins, it appears on the calendar the same week.
What a running calendar prevents
A filing calendar with nobody running it is one of the first operational failures after a death. When the calendar lives with the office, it survives the person. The companies keep filing, the records keep updating, and the deadlines keep moving in the right direction, because the calendar moves them. The work of running it does not depend on anyone's memory or attention span. It depends on a list, maintained.