(a) Upon passage of the budget by the annual Town meeting, the amounts stated therein as the amount to be raised by property taxes shall constitute a determination of the amount of the levy for the purposes of the Town in the corresponding tax year, and the selectmen shall levy such taxes on the grand list furnished by the listers for the corresponding tax year.

(b) The selectmen shall likewise levy such taxes for the purposes of meeting the budget of the Middlebury Incorporated School District No. 4 and paying the amount which the Union School District No. 3 assesses the Town. In the event the Union School District No. 3 has not passed a budget at the time the selectmen levy such taxes, the selectmen may, in their sole discretion, base such levy on the prior tax year assessment to the Town by the Union School District No. 3. In such case, after the passage of the Union School District No. 3 budget and assessment to the Town, the selectmen may adjust the levy of such taxes and the Town shall credit the taxpayers for payment of property taxes for the year accordingly.