First check: is this a medical problem in disguise?
When a cat who was reliable suddenly stops using the tray, health is the first box to tick, not the last. Cats who find urinating uncomfortable often associate that discomfort with the tray and begin trying other surfaces, and cats passing urine frequently in tiny amounts, straining with little result, licking themselves more than usual, or crying in or near the tray need a veterinarian promptly, the same day if a male cat cannot pass urine at all, as that is an emergency. Defecation changes count too: hard stools, diarrhoea, or pain around the back end can all produce a cat who avoids the tray for bowel motions while still urinating in it. Even if your cat seems bright and is eating, book a check when the change is sudden, because early urinary and digestive problems are far easier to sort than established ones, and a behaviour plan built on top of untreated discomfort will fail.
Second check: walk the tray audit in your cat's order
Once urgent health signs are ruled out or while you wait for the appointment, audit the tray exactly as your cat experiences it. Is it clean by her standards, scooped today, with litter at the depth she likes? Has anything about it changed in the last fortnight: a new litter, a liner, a hood added or removed, a different cleaning product, a move to beside the tumble dryer? Can she actually get to it freely at night and when visitors are in the house, and can she step in without climbing if her joints are stiff? In a multi-cat home, watch whether another cat waits near the tray or chases her when she leaves it, since ambush at the exit is a well-known reason a cat quietly gives up on a perfectly clean tray. Finally, look at where she is going instead. A soft pile of laundry suggests she wants a soft surface, the bath suggests she wants a cool clean one, and a spot by the door suggests anxiety about something outside.
Third check: what changed in the household around the same time?
Cats keep mental maps of safe routines, and tray avoidance often dates from a disruption rather than from the tray itself. Building work, a new pet, a visiting dog, a change in your working hours, new furniture over an old toileting spot, or outdoor cats visible through a window can all tip a cat into choosing a place she considers safer. Write down the date the accidents started and anything that changed in the week before, however trivial it seems, because that timeline is exactly what a vet or behaviour professional will reconstruct with you. Then restore predictability: keep feeding and play times steady, add a second tray in a different quiet location as an experiment, and clean accident sites with an enzymatic cleaner so scent does not keep drawing her back. Avoid scolding or placing her in the tray to show her, which adds stress to the very place you need her to trust.
Putting the findings together for the vet visit
Arrive at any appointment with specifics rather than impressions: how many accidents, where, urine or faeces or both, what the tray setup looks like, and what changed at home. A short dated log kept for a week is more useful than a month of worried recollection. If the vet finds no medical cause, that log becomes the foundation of a behaviour plan, and if treatment is needed, it shows whether the tray use recovers as comfort returns. KinsLe Pet Passport is built for exactly this kind of visit, holding your cat's records and your dated observations together in one portable packet you can hand over rather than reconstruct from memory.