- March 1 – Farmers and fishermen who did not make 2016 estimated tax payments must file 2016 tax returns and pay taxes in full.
- March 2 – Large employers must furnish Form 1095-B and Form 1095-C to employees.
- March 15th – 2016 Partnership and S-Corporation returns with a December 31st year end are due or must file an extension.
- March 31st – Forms 1095-B and 1095-C due to the IRS, if filing electronically. (Employers who have 250 or more employees are required to file electronically.)