W-2 Electronic Filing
Section 143.591, RSMo, requires employers with 250 or more employees to submit the Form MO W-3 and accompanying Form W-2’s electronically;
- The file must follow the Social Security Administration's EFW2 format along with Missouri modifications as outlined in the Missouri Employer Reporting of W-2s Instructions and Specifications.
- The file must be submitted by January 31.
While it is not statutorily required for employers to provide their 1099 files electronically, beginning 2018 for tax year 2017, Missouri will be accepting 1099 files through the same upload process being utilized for W-2 reporting.
The Missouri 1099 Reporting Requirements and Specification Handbook is designed to be used as a companion to the Internal Revenue Service Publication 1220. The handbook highlights the special requirements of the Missouri electronic filing program.
Electronic Filing Access
- The above link can be used to submit an electronic W-2 or 1099 file if you are a Missouri employer with an active employer withholding account. Use the current Missouri Tax ID and PIN number to gain access.
- If you do not know your Missouri Tax ID or PIN number, you can contact our taxpayer assistance phone lines by telephone at 573-751-7200, by email at firstname.lastname@example.org, or by fax at 573-522-1722.
- You will receive a confirmation number after the file is successfully uploaded. Keep this confirmation number for your records.
Third party payroll agencies filing for Missouri clients, that do not have a Missouri Employer Withholding account and did not register with us last year, will need to send an email to email@example.com to request an MO-W3 Submission Account. Please include the responsible person’s name, email address, and phone number in your request.
Software developers and payroll agencies interested in testing format changes for the current year should send an email to firstname.lastname@example.org with your company’s name and contact information for the person who will be submitting test files. We will provide you with the information for accessing and submitting a test file.