ret ‧ ro ‧ ac ‧ tive /ˌretrəʊˈæktɪv◂ $ -troʊ-/ BrE AmE adjective formal
a law or decision that is retroactive is effective from a particular date in the past SYN retrospective :
a retroactive pay increase
retroactive to
The legislation is retroactive to 1st June.
—retroactively adverb