VERB
追溯；使（從過去某個日期）開始生效
If a document or an arrangement is backdated, it is valid from a date before the date when it is completed or signed.
例句
The contract that was signed on Thursday morning was backdated to March 11...
周四早上簽訂的合同實際生效日期追溯到3月11日。
Anyone who has overpaid tax will be able to backdate their claim to last April.
超額納稅者申領退款可以從去年4月算起。