A claim for credit or refund shall be filed with the Director in writing and shall state the specific grounds upon which it is founded. The Director may by regulations prescribe the information to be included in a claim. A claim may not be amended after the last date prescribed by § 539 of this title for filing a claim for credit or refund if the net effect of the amendment would be an increase in the amount of the overpayment.
68 Del. Laws, c. 187, § 1.