Start by having the chip read
A microchip does nothing until someone scans it, so the first check is physical. Ask your vet, or the nurse at a routine appointment, to pass a scanner over your cat and read the number back to you. This confirms three things at once: the chip is still transmitting, the number is legible and complete, and the chip is roughly where it should be, between the shoulder blades. Chips occasionally migrate under the skin as a cat ages, sometimes down a shoulder or along the side, and a scanner swept over the whole body finds a wanderer that a quick pass over the neck would miss. Write the number down exactly as read, digit for digit.
Match the number to the registration
The chip number on its own identifies nothing; the value sits in the registry entry it points to. Your adoption paperwork, the certificate from when the chip was implanted, or a previous vet invoice will usually show which registry holds the record. Contact that registry — most let keepers view and update their entry online or by phone — and confirm that the number you were given at scanning is the number on the record. If the two disagree, or if no record exists for the number at all, the registry and your vet can work out where the registration went astray, which occasionally happens when a chip was implanted but the paperwork was never completed.
Check every line as if a stranger depends on it
Because one day a stranger will. The person who scans a found cat rings the first number on the record, so check the entry the way they will use it. Is your name spelled as you would expect? Is the mobile number your current one, digit by digit, rather than the phone you replaced two years ago? Is the address the house you actually live in? Is there a second contact — a partner, a family member — who could answer if you are abroad or your phone is off? Moves, new phones and relationship changes are the three moments chip records quietly go stale, so treat each as a prompt to update the entry.
Build the check into the year
Once the record is right, keeping it right is cheap. Ask for a quick scan at the annual health check so migration or a failing chip is caught while your cat is sitting in front of you rather than missing. Check the registry entry at the same time each year, and update it the week you move house or change numbers rather than adding it to the unpacking pile. If your cat is ever rehomed, the registration must be transferred to the new keeper as part of the handover, with the registry notified by both sides.
When something turns out to be wrong
A chip that cannot be found on a thorough whole-body scan, or a record registered to a previous owner or an old address, is worth sorting the same week. Your vet can advise whether a second chip should be implanted if the original has failed or travelled somewhere unreadable, and registries can correct ownership records with proof of keepership. Do not assume a collar tag covers the gap: collars come off, chips do not. Keeping her chip number inside her KinsLe Pet Passport means the number travels with her vaccination history and other records as one packet, so a new vet, a cattery or a border official can see the whole picture without you hunting through drawers for certificates.