M-Form Late Filing Penalty

April 22, 2021

To: Manufacturers, Real Estate Owners and Preparers


  • Disregard this reminder if you have already filed your 2021 M-Form
  • 2021 M-Form extended filing deadline was Thursday, April 1, 2021

IMPORTANT – Note to Recipient

Your email address is associated with the manufacturing account identified in the subject line as an authorized user within the Wisconsin Department of Revenue's (DOR) Manufacturing Assessment System (MAS).

Take action - if you are the:

Filing M-Forms late – after April 1 extended deadline

Under state law, all manufacturers with a filing extension must file the 2021 Manufacturing Property Return (M-Form) by April 1, 2021.

Electronically file (e-file) your M-Form

DOR recommends e-filing your 2021 M-Forms through our Manufacturing Assessment System (MAS). M-Forms can still be e-filed after the April 1, 2021, extended due date. The MAS system automatically time stamps returns when the preparer designates the form as complete. Penalties are assessed based on the e-file date.


To avoid a delayed response, contact the district office in your area.