CollarPassAn ISO microchip is the anchor for every other document in a pet's travel file. Border staff scan it, the vaccination record refers to it, and a rabies antibody report is only meaningful if it carries the same number. Most microchip problems at a border are not medical. They are a vaccination given before the chip went in, a number that does not match the certificate, or a chip the scanner cannot read.
The standards involved are ISO 11784 and ISO 11785, and it helps to know what an inspector checks when citing them. This guide covers dogs, cats and ferrets on ordinary non-commercial routes; CollarPass does not implant chips, sell readers or issue documents.
Sources: GOV.UK microchip rules, Japan AQS step 1, and European Commission entry conditions — checked November 11, 2026.
Quick answer
- An ISO 11784/11785 chip carries a 15-digit numeric code that standard scanners read.
- Implant it before, or on the same day as, the first rabies vaccination. An earlier vaccination may not count.
- The same number must appear on the vaccination record, health certificate and any titer report.
- A non-ISO or unreliable chip can mean carrying your own reader, rechipping, or refusal at the border.
- Tattoo exemptions are narrow: a legible tattoo applied on or before 3 July 2011, in most cases.
Sources: GOV.UK and Japan AQS — checked November 11, 2026.
What the two standard numbers mean in practice
GOV.UK, Japan's Animal Quarantine Service (AQS) and the European Commission all name the same two standards. Staff on approved air, train and ferry routes to Great Britain check a chip against ISO 11784 and ISO 11785; AQS spells out the format it expects, a 15-digit code of numbers only; the EU requires an implanted microchip and cites Article 70a, point (a) of Delegated Regulation (EU) 2019/2035 for the technical specification.
None of those pages asks for a particular brand. The Centers for Disease Control and Prevention (CDC) says a dog's microchip can be any brand but must be detectable with a universal scanner. So the useful question is not "which chip is approved?" but "will a standard reader at this border display the number printed on my paperwork?"
| Destination | What the rule asks for | Where the requirement sits |
|---|---|---|
| Great Britain | ISO 11784/11785 chip, read on approved routes; non-ISO chips may need your own reader | GOV.UK microchip guidance |
| European Union | Implanted microchip; vaccination must not predate identification or the recorded reading | Regulation (EU) 2026/131, Article 13 refers to the chip requirements in Regulation (EU) 2019/2035, Article 70a |
| Japan | ISO 11784/11785 chip, 15 numeric digits, implanted before the first rabies vaccination | Japan AQS, step 1 |
| United States | Any brand, readable by a universal scanner; number on every required document | CDC dog import FAQs |
The two EU regulation numbers describe complementary parts of the rules. Regulation (EU) 2026/131, Article 13, governs identification for non-commercial entry from third countries and refers to the transponder specifications in Regulation (EU) 2019/2035, Article 70a; they are not alternative names for the same regulation.
Sources: GOV.UK, European Commission, Japan AQS, and CDC — checked November 11, 2026.
The order that matters: chip first, then rabies
Every system in this guide links the rabies vaccination to the identification, which is why the sequence is checked before anything else.
For EU entry, the vaccination date must not precede the date the microchip was implanted or read. For Great Britain, the pet must be microchipped before or at the same time as the rabies vaccination; otherwise the pet has to be vaccinated again. Japan requires the chip before the first rabies vaccination and states that a vaccination given before implantation is invalid, with only narrow documented exceptions. CDC requires a U.S.-issued rabies vaccination to have been administered after the dog's microchip was inserted.
If your pet was vaccinated first and chipped later, do not assume the record can be reordered. Ask the destination authority and the certifying veterinarian what the fix is, because the usual answer is a new vaccination and a new waiting period.
Sources: European Commission, GOV.UK, Japan AQS, and CDC — checked November 11, 2026.
What the vet should write down
Ask for the full number, not the last few digits, and for the implantation date to be recorded beside it. GOV.UK requires the number in the pet passport, animal health certificate or Great Britain pet health certificate, with the date shown before the vaccination dates. Japan AQS asks owners to check the chip number at each stage of its import process, a useful habit everywhere.
GOV.UK also lists who may implant a travel microchip: a veterinarian, a vet nurse or student under a vet's direction, someone trained before 29 December 2014, or someone assessed on an approved training course.
Sources: GOV.UK microchip guidance and Japan AQS — checked November 11, 2026.
What border staff actually do with it
The scan is a matching exercise. Japan AQS explains that a chip normally contains only a unique identification number, with no vaccination history, and that it is scanned on arrival to see whether it matches the health certificate. A chip that reads a different number stops the process even when the pet is healthy and vaccinated.
The consequences are specific. GOV.UK says a pet will be refused entry or quarantined if its microchip cannot be read on entry or return to Great Britain. CDC says a dog from a high-risk country whose chip cannot be scanned on arrival may be denied entry and returned at the importer's expense.
Sources: Japan AQS microchip FAQ, GOV.UK, and CDC — checked November 11, 2026.
When the chip cannot be read
GOV.UK separates two situations. If the chip cannot be read at all, preparation usually restarts: rechip, revaccinate, take new blood tests if travelling from a country that is not listed, and issue a new document recording both chip numbers. If the chip can only sometimes be read, a vet who obtains a reading may implant a second chip without removing the original, recording the old and new numbers, the date they were read, the insertion date, and signing and stamping the page.
Japan treats unreadable or duplicated chips as an import problem. AQS says a non-ISO chip may require you to bring a compatible reader, that numbers beginning "900 202" were not accepted as identification at the time of writing, and that duplicate numbers have been reported, in which case a new chip and repeat procedures may be necessary. Contact the quarantine service at your arrival port early if any of this applies.
Sources: GOV.UK and Japan AQS — checked November 11, 2026.
Tattoos and other narrow exemptions
Great Britain accepts a tattoo instead of a microchip only when it was applied on or before 3 July 2011, is clearly legible, and the pet was vaccinated against rabies after tattooing, with the details recorded. The EU also allows a clearly readable tattoo applied before 3 July 2011. Japan offers no tattoo route: its process is built around a chip read at each step.
A tattoo that satisfies one destination can fail another. If your pet has an old tattoo and you are considering Japan, the United States or a route with a titer test, treat the microchip as required and ask the destination authority before paying for anything else.
Sources: GOV.UK and European Commission — checked November 11, 2026.
Five checks before you book anything
- Have the chip scanned at the clinic and compare the displayed number with the vaccination record.
- Confirm the implantation date is on or before the first rabies vaccination date.
- Ask whether the chip is ISO 11784/11785 compliant, and write the answer down.
- If the number begins with a digit other than 9, ask the vet to confirm it reads on a universal scanner, as CDC suggests.
- Photograph the reader screen and the implantation certificate, then carry both.
Once the identification is clean, move on to the international health certificate and, where a blood test applies, the rabies titer guide. Check the destination through country requirements before booking a flight, and see pricing if you want the dates laid out for your route.
Sources: CDC, GOV.UK, and Japan AQS — checked November 11, 2026.
