Three cats on three different booster schedules defeat the single reminder on the calendar, because each date belongs to a different animal, a different vaccine history and a different certificate.
One Cat, One Line, One Certificate
Give each cat her own line on one household page: her name, what her last vaccination covered, the date it was given, and the next due date copied from her own certificate. Never assume the three match. Cats adopted at different times, from different rescues or practices, arrive on staggered schedules, and boosters given late or early in one year shift the next. The certificate is the source of truth for each cat — not the pattern of the cat vaccinated before her.
The Month-Ahead Reminder
Set a reminder a month ahead of every due date, not on the date itself. A month leaves room to book an appointment at a practice that may be busy, to arrange transport for a cat who hates the carrier, and to notice if money or timing needs juggling across three separate visits. Do not rely on the practice's reminder system alone to catch every cat in a multi-cat household; cards get addressed to one animal, or arrive after a house move, and a missed booster can mean restarting a course rather than topping one up.
Updating After Each Appointment
When one cat is vaccinated, update only that cat's line, and do it the same day. Photograph the new certificate straight into her section before it reaches the drawer where paperwork goes to be forgotten, and check the due date the vet has written rather than adding a year by habit — intervals differ by vaccine. A five-minute update after each visit is what keeps the page trustworthy; a page reconstructed from memory in a hurry is where dates quietly go wrong.
When the Page Earns Its Keep
The system proves itself on the awkward days: a sitter who needs to know which cat is covered, a cattery that asks for proof before a booking, or a vet visit where one cat's history matters and the other two are noise. Because each record sits with the right cat, the answer is a look at one line, not a search through a shared folder of certificates. A Pet Passport in KinsLe gives each of the three cats her own packet — records, dates and notes held together — so when a booster month arrives, the proof is already in your hand rather than in a drawer you still have to search.