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[US] Missouri state tax registration guide

United States: Taxes

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This guide is an overview of registering your business for Missouri state payroll taxes. For more support, contact the state agency directly.

This guide includes key payroll tax requirements, links to state agency portals, and instructions for granting third-party access to Wave's partner. These steps are required to complete your tax profile in Wave so we can manage your payroll tax payments and filings on your behalf.

Tax requirements

To pay employees in Missouri, you may need to register for the following taxes:

Missouri Withholding Tax and Unemployment Insurance (SUI) Tax

The Withholding and Unemployment Insurance taxes use a single registration portal. 

During registration, ensure you select both the Withholding and Unemployment Insurance taxes. Once done, create a MyTax Missouri Account (Withholding) and set up a UInteract Account (Unemployment) to manage your taxes online. 

You also need to grant Wave's partner third-party access. 

Local Earnings Tax

Some municipalities impose local earnings tax. Registration is required at the city level if you operate in these jurisdictions:

  • Kansas City: Go to the Kansas City Quick Tax Portal. Once registered, provide the Letter ID to Wave for filing and payment access
  • St. Louis: Complete Form E-9. Submit by fax to (314) 622-4847 or email to EarningsTaxCOR@stlouis-mo.gov

St. Louis requires employee earnings to be reported for tax purposes. If you have employees who reside in St. Louis, you must register for this tax account even if no St. Louis earnings tax is withheld from their wages.

Third-Party Administrator (TPA) access

Withholding Tax TPA access

To authorize TPA access for Withholding Tax:

  1. Log in to MyTax Missouri.
  2. Select Manage Accounts.
  3. Choose I would like to give access to MyTax Account.
  4. Enter your business account information.
  5. Confirm authorization for Check.

UInteract TPA access

There is no formal third-party access process through UInteract. If needed, Wave will provide instructions based on case-specific requirements.

Complete your payroll  tax profile

After completing the registration steps, complete your payroll tax profile. Be sure to update your account with your:

  • Missouri Withholding Account ID
  • Missouri UI Account Number

Additional Support 

For help with your tax account, registration, or technical errors, contact the state agency directly: