Vt. Stat. Ann. tit. 32, § 5872

In the case of corporations, if the income tax liability is, or is expected to be, in excess of $500.00, the income tax liability imposed by this chapter shall be discharged in accordance with subchapter 5A of this chapter; any balance due shall be paid on or before the date on which the return of the corporation for the taxable year is required to be filed (determined with regard to any extension of time for filing). Payments made under extension are subject to interest pursuant to section 5868 of this title.