The letters Y, K and W (which have not been used until now) are to be used, following the Portuguese Language Orthographic Agreement of 1990, implemented in 2008.

The first registration plate in Portugal was on 1 January 1937 and until 29 February 1992, the “AA-00-00” model was used. From 1 March 1992, the “00-00-AA” model was used.

After that one, the “00-AA-00” model began to be used, which remains in use until today.