Please be advised, Massachusetts law was changed to conform the filing due dates for Massachusetts C corporation tax returns to federal filing due dates, beginning with tax returns due on or after January 1, 2018. C corporations are now required to file their tax returns on or before the 15th day of the fourth month following the close of each taxable year (April 15th in the case of corporations filing on a calendar year basis). The law did not change the filing due date for S corporation tax returns, which remains the 15th day of the third month following the close of each taxable year. The laws governing estimated tax payment requirements for corporations were not changed. For further details see TIR 17-5.
Payments made with a return, including extension payments, estimated tax payments and withholding, are considered to be paid on the last day prescribed for the filing of the return and/or the payment of the tax, without regard to any extensions. See, G.L. c. 62C, § 79. Therefore, any overpayment from a prior year return will be considered to be paid as of the prior year return due date. For example, if a calendar year C corporation reported an overpayment on its 2017 corporation excise tax return and elected to apply it as a credit to its 2018 estimated tax, the payment will be credited as of April 17, 2018, which is the 2017 return due date and about one month after the due date of the first estimated tax installment payment for the 2018 tax year. To avoid the imposition of underpayment penalties the first estimated tax installment should be paid on or before the first installment due date, not the return due date. No credit may be applied to any estimated tax other than 2018.