30 Del. C. § 1168: Time and place for filing returns and paying tax.

The income tax returns required by this chapter shall be filed on or before the thirtieth day of the fourth month following the close of the taxpayer’s taxable year. A person required to make and file a return under this chapter shall, without assessment, notice or demand, pay any tax due thereon to the Department of Finance on or before the date fixed for filing such return. The Secretary of Finance shall prescribe the place for filing any return, declaration, statement or other document required pursuant to this chapter and for the payment of any tax.