The papers worth keeping for any cat
A good cat file is not every scrap that mentions her. It is the set that answers urgent questions quickly: who she is, what care she has received, what she needs, and who may make decisions for her. Keep her vaccination record, microchip registration details and chip number, adoption or purchase papers, and any formal breed papers or shelter history you were given. Add visit summaries and discharge notes from her clinic, laboratory results, imaging reports, and a note of ongoing conditions or daily medicine she receives. Insurance documents, if she is covered, belong here too, along with boarding or sitter instructions you have used and trust.
A one-page summary that sits on top
The most useful single sheet in the folder is a summary you write yourself. List her name, age or best estimate, breed or description, markings, chip number, clinic name and phone number, your number, and a backup contact who knows her. Note what she eats, how much, and when, plus any allergies, long-term conditions, and the fears or handling quirks staff should know, such as hating the carrier or needing a towel wrap for nail trims. Update this page whenever something on it changes, because it is the page a sitter, emergency clinic, or family member will actually read under pressure.
Organizing the folder so it stays usable
Use one binder, accordion folder, or clearly named digital folder with sections that match how the papers are used: Identity, Vet Care, Medicines and Conditions, Insurance, and Care Instructions. Put the newest document at the front of each section so the current vaccination status or latest blood result is found first, and remove or clearly mark papers that have been replaced, such as an old insurance schedule. Fight clutter by filing after each visit rather than saving a shoebox of receipts for a yearly sort. A file you can open to the right page in under a minute is a file you will keep maintaining.
Paper, digital, or both
Paper survives a dead phone battery and can be handed across a counter, while digital copies survive a house fire and can be sent to a new clinic before you arrive. Keep both: the folder at home, and a scanned copy of every important page in a phone album or cloud folder with plain names that include your cat's name and what the document is. Photograph new pages the day they come home. If you and a partner share her care, agree on the one shared location so two half-files never form in two houses.
The yearly tidy that keeps it honest
Once in a while, read the folder cover to cover. Check that the chip registration still shows your current phone number and address, that the summary page matches what she actually eats now, and that expired insurance or boarding papers are not masquerading as current ones. That same tidy file is what a new veterinarian, a boarding stay, or an emergency visit will thank you for, because nobody has to reconstruct her story from fragments. The KinsLe Pet Passport is built for exactly this habit, keeping your cat's records together in one portable packet instead of scattered drawers.