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;

To electronically transmit your W-2s, follow these steps.

  1. Register – Obtain your W-2 transmitter ID and test and production passwords. Click here to request your ID and password. Note: If you are using a third-party service or program you may not need to register to transmit. Check with your payroll service or software program to see if it includes W-2 file transmission.
  2. Create your file to transmit. Develop the file following the Social Security Administration’s Publication No. 42-007, Specifications for Filing Forms W-2 Electronically, and the additional Missouri requirements in our Employer Reporting of W-2s Instructions and Specifications (Important: compressed files, PDF files or spreadsheet files, such as Excel, are not accepted).
  3. Choose your method of transmitting the file to Missouri.
    1. Simple web file upload – This is the easiest free method available for transmitting W-2s. Simply logon to this secure online application using your web browser, enter your W-2 transmitter ID and password, browse for your W-2 file, and select the file to upload it. This method does not require any software download or programming.
    2. Write your own custom code for automated processing to transmit your file. You may connect to our server to upload files via an FTP client with 128 bit SSH capabilities. Bulk filers and third-party payroll programs and services may prefer custom coding to transmit W-2s by interfacing directly with Missouri Department of Revenue's Gateway.
  4. Transmit your file. Make sure you have a successful upload and retain a copy of that page for your records. If the file cannot be processed, the user will be notified by email. Any reject is a reject of the entire file. The email will contain a subject of “EFW2 Rejected”, the email will include recommendations on how to correct the file. When resubmitting a file after a reject be sure to upload the entire file, as if you are submitting for the first time.

1099 Reporting

While it is not statutorily required for employers to provide their 1099 files electronically, beginning 2018 for tax year 2017, Missouri will be accepting those files through the same type of bulk 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.

**Testing Period**

Test files may be submitted starting Monday October 16, 2017. We recommend and encourage filers to submit a test file on our website using the W2 Bulk Upload Testing Submission Folder. If a test file is larger than 10MB, please call 573-751-8150 to have size limitation increased. Test files will provide validation for proper format and identification of problems before production data is submitted, avoiding delays in processing. Please notify the Department at when a test file has been submitted. Test files should be labeled as TEST at the beginning of the file name, TEST_TY2017W2_ABCCompany_21123456_12182017.txt.