Delaware Code
Subchapter VIII. Returns and Payments of Tax
§ 1165. Change of status as resident or nonresident during the year.

If an individual changes status during the taxable year from resident to nonresident or from nonresident to resident, the individual shall file a return for that portion of the year during which the individual is a resident and the State Tax Commissioner may, by forms or instructions, require the individual to file a return for that portion of the year during which the individual is a nonresident.