Relocating with a cat or dog fails on sequence more often than on paperwork: several requirements have to happen in a fixed order, and doing them out of order invalidates the earlier step rather than merely delaying it. Anyone booking flights before checking the timing risks having to move the date.
Order matters here more than people expect: the microchip has to go in before or on the same day as the rabies vaccination, not after — a rabies shot given before the chip is officially invalid for travel purposes. The animal needs to be at least 12 weeks old for that first vaccination, and it only becomes valid 21 days later, so you're looking at a minimum three-week runway before travel regardless of anything else. If you're coming from within the EU, an EU pet passport recording the chip and vaccination is generally sufficient. Coming from outside the EU, you'll need an EU health certificate instead, and entry has to happen through a designated EU entry point where the animal gets checked in. If your pet is coming from, or has passed through, a country the EU classifies as high-rabies-risk, add a rabies antibody blood test done well before departure — testing after you've already left triggers a 90-day wait before the animal can travel. Because entry-point and country-specific rules shift, check the current requirements for your exact country of origin on the NVWA or LICG websites before booking anything irreversible.