1. A change or alteration made to a document, contract, law, or agreement that applies to a period before the modification was made
The retroactive modification of the contract affected payments dating back to January.
A modificação retroativa do contrato afetou pagamentos retroativos a janeiro.
2. In legal or administrative contexts, an adjustment that takes effect from an earlier date than when it was officially implemented
The tax law included a retroactive modification that applied to the previous fiscal year.
A lei tributária incluiu uma modificação retroativa que se aplicava ao ano fiscal anterior.