retroactivelyadverb
uk/ˌretrəʊˈæktɪvli/usLAWwith effect from a date in the past before a law, decision, etc. was approved:
The legislation applies retroactively to January 1.
A student can apply after the fact, and we'll process it retroactively.
The management retroactively approved some of those expenditures.
See also
retrospectively