Any law which shall have the effect of increasing the rates of taxation on personal income for any year or part thereof prior to the date of the enactment thereof, of for any year or years prior to the year in which the law is enacted, shall be void.
Retroactive increase of taxation of personal income
Del. Const. art. VIII, § 9 — under Revenue And Taxation.
Del. Const. art. VIII, § 9
Retroactive increase of taxation of personal income