EASA
The ICAO Amendment 174 to Annex 1 -Personnel Licensing- enables, within a group of States, the automatic validation of licenses issued by any State of the group when those States are party to a formal agreement under common licensing regulations. Such formal agreements can be implemented in various regions and improve the mobility of licensed personnel. It can be introduced with the support of a regional safety oversight organization, as appropriate. The amendment to Annex 1 is applicable by 9 November 2017.
Based on the above and in accordance with regulation EU no. 1139/2018, art. 67, pilot licenses issued by EU member States are automatically validated, the Competent Authority shall issue the license with the remark on the license item XIII: ‘This license is automatically rendered valid as per the ICAO attachment to this license', and provide the holder of the license with the ICAO attachment.
ICAO
Pilot licences issued by ICAO Contracting States can be validated in accordance with european regulation (EU) no. 723/2020.