What happens when VIES is temporarily unavailable?

VIES is shared infrastructure across 27 national tax authorities and has occasional outages, sometimes affecting just one country. If no requester VAT is configured in dashboard Settings, vatnode first tries the national-registry fallback for supported countries, so many checks still get an answer while VIES is down. When a check can't be completed and no fallback succeeds — or a requester is set, which deliberately skips the fallback to preserve the consultation number — vatnode returns HTTP 503 with the code VIES_UNAVAILABLE, which is very different from an "invalid" result. The error reference documents this and every other error code in full; live status shows current VIES and national-fallback health per country. The right pattern is to treat VIES_UNAVAILABLE as a signal to retry later rather than to reject the customer.