ICAO English proficiency exam is one of the qualifications that all professional pilots must have valid and endorsed in their flight crew license. ICAO English validity is monitored and must be up to date along with the medical certificate and type rating or class rating.
If your ICAO English language proficiency is expired, you cannot act as a pilot - active flight crew member on board of the planes performing international flights and planes within the commercial air transport.
A similar restriction applies to air traffic controllers. In case your language proficiency has expired, you cannot act as an ATC.
ICAO English language proficiency revalidation is same as the exam. The content of the ICAO English exam is uniform. It doesn't matter whether it's your first exam, revalidation, or renewal.
If your ICAO English validity has expired, there's nothing easier than just letting us know so we can arrange a date of your ICAO English exam.