An extension is not necessary when you expect to claim a refund. If you don't have a federal extension, file an Application for Extension of Time to File Michigan Tax Returns (Form 4 ) with your payment.Business tax filers must use this form to request an extension and must file it even if the Internal Revenue Service has approved a federal extension. You can only eFile and IRS tax extension, but not a Michigan extension. The tax extension will only avoid late filing penalties until the October deadline. You'll receive an electronic acknowledgment once you complete the transaction. Keep it with your records. If you have an approved 6-month Federal extension (IRS Form 4868), you will automatically receive a Michigan tax extension for the same amount of time. This gives you until October 15 to file without penalties. An extension of time to file your return does not grant you any extension of time to pay your taxes.