Recognizing that a geographic area may no longer qualify as a TEA as conditions change over time, particularly if USCIS processing times are long, USCIS allows for such change by focusing on when the when the investment is made or when the I-526 petition is filed, whichever occurs first.
When USCIS adjudicates the I-526 petition, a project is found to be in a TEA at the time of the investment or at the time of filing the I-526 petition.
USCIS typically defers to the state government authority’s conclusion that a project is located in a TEA as evidenced by the TEA letter. TEA letters are usually valid for one year and are often updated every May.
See USCIS manual: