Public Act 8 of 2009 is now law, effective retroactive for tax years beginning after 12/31/2007, it amends the Michigan Business Tax to allow a taxpayer that calculates and pays estimated payments for federal income tax purposes under Internal Revenue Code Section 6655(e) , to use the same methodology as used to calculate the annualized income installment or the adjusted seasonal installment, whichever is used as the basis for the federal estimated payment, to calculate the estimated MBT payments required each quarter.  A penalty for underpayment of an estimated MBT will not be assessed for a tax year that ends before December 1, 2009 if the taxpayer paid 75% of the tax due for the tax year. 

The Michigan Department of Treasury has stated that for now they will follow FAQ A36 and allow an overpayment made in connection with the annual return to be applied as timely against the taxpayer's first quarter MBT estimate, even though the overpayment may have been made after the due date for the first quarter MBT estimated payment.