In a single-cat home, a shoebox of paper works after a fashion. Add a second or third cat and the failure mode appears at once: a vaccination page filed under the wrong name, a weight note nobody can attribute, a chip number that might belong to either tabby. The fix is structural, not tidier intentions.
One Shared Household Section in Front
Start the file with one household section that belongs to no individual cat. Into it go exactly the shared items: joint insurance that covers several cats, sitter instructions for the house, and emergency contacts who can reach you or authorise care. Keeping shared paper out of per-cat sections matters, because anything placed inside one cat's section will later be read as that cat's own record. Label the household section plainly as household, in a neutral colour no cat uses, and resist adding per-cat pages to it during a busy week. When a vet prints a summary covering two cats seen together, photocopy or photograph it, place a copy into each cat's own section, and file the original in the household section.
One Colour and Labelled Section per Cat
Assign each cat a colour and use it everywhere: section divider, folder spine, sticky notes, even the pen you write that cat's name with. Each per-cat section holds exactly five components, always in the same order: chip details with its registration letter, vaccination pages in date sequence, weight notes from each visit, a summary of every visit, and a current photo. Those five, in that order, for every cat, so your hand learns the system once. The rule that protects the whole structure is simple: nothing gets filed unlabelled, ever. If a loose printout lacks a name, it waits on top of the file until you confirm which cat it belongs to, even if that takes a phone call to the practice. A certificate in the wrong history is worse than a certificate temporarily unfiled, because nobody questions a confidently filed page.
Phone Folders That Mirror the Paper Exactly
Photograph key pages as they arrive and store them in a phone folder named for the individual cat, headed by a clear photo of that cat as the folder's opening image. That heading photo does real work: when you scroll quickly at a reception desk, the cat's face confirms you opened the right folder before you show any document. Keep the phone folders in the same cat order as the paper file, and name weight notes and visit summaries with the visit type included, so a search inside the folder finds them fast. Update the current photo in both places as markings, collars or body condition change, since an old kitten photo undermines identification for an adult cat.
Habits That Keep the System Honest
File on the day paper arrives, while you still remember which cat was seen. At each vet visit, say each cat's name aloud at the desk and check printed pages carry the right name before you leave, because practices serving multi-cat homes make transcription slips too. Once a year, flick through every section checking that each page names its own cat, and move strays with a note rather than silently. When a new cat joins the household, assign the colour and build the section before the cat arrives home, because the first vet printout and the first photographs appear within days and will otherwise be dropped into whichever section sits on top. Discipline like this is precisely what the designers of KinsLe Pet Passport assumed, with separate packets per animal letting a sitter or vet lift out a single cat's history while the rest of the household file stays untouched.