Relating to overpayment of personal income tax; and prescribing an effective date.

Provides that if taxpayer elects to apply overpayment of tax to subsequent year estimated tax installment, amount paid is credited as estimated tax on later of first estimated tax due date or date payment is made, if elected on timely filed return, or is credited as estimated tax on later of date return is filed or date payment is made, if elected on return filed late. Applies to payments made in tax years beginning on or after January 1, 2018. Takes effect on 91st day following adjournment sine die.