Mich. Admin. Code R. 206.23
Rule 23. The income tax withheld from compensation paid to employees is a personal obligation of the employer (taxpayer) and is due and payable on or before the fifteenth day of the month next succeeding the month in which the tax was withheld. The commissioner of revenue may require filing of returns on other than a monthly basis. The taxpayer shall make out a tax return for the preceding month on the form required by the department, showing the amount of the tax for which he is liable and mail the return, together with a remittance for the amount of the tax, payable to the state of Michigan, to the address as indicated on the return, on or before the fifteenth day of the month. The return shall be signed by the taxpayer or the duly authorized agent of the taxpayer.
Mich. Admin. Code R. 206.23