Missouri recently issued several regulatory updates affecting withholding tax, the division of income and estimated tax payments between spouses, corporate income tax filings, and certain sales and use tax exemptions. While many of these changes clarify existing rules or update administrative procedures rather than introducing entirely new tax policies, they still carry important compliance implications for employers, corporate taxpayers, and certain industries operating in Missouri.

Understanding how these updates apply to your organization can help prevent reporting errors, avoid unexpected tax liabilities, and maintain compliance with the Missouri Department of Revenue.

Below is an overview of the key regulatory updates and considerations for businesses.

Missouri Clarifies Withholding Requirements for Out-of-State Employees

Missouri amended its withholding tax regulation (Mo. Regs. Title 12 §10-2.015) to clarify how employers must handle withholding for Missouri residents who work outside the state.

Under the updated rule, Missouri residents working in states that do not impose an individual income tax remain subject to Missouri withholding requirements. In addition, if a Missouri resident works in a state with a lower income tax rate than Missouri, employers must withhold the difference between the two states’ tax rates.

The revised regulation also updates several administrative procedures related to employer withholding accounts, including:

• Clarification of employer compensation deductions
• Procedures for closing withholding accounts when ownership changes
• Registration and recordkeeping requirements for certain employers and withholding agents

For organizations with remote or multistate workforces, these changes reinforce the importance of reviewing payroll systems and withholding practices to ensure they properly account for employees who reside in Missouri but perform work in other states. Employers managing distributed teams may also benefit from reviewing guidance on multi-state payroll tax obligations for remote employees.

Corporate Groups See Changes to Consolidated Income Tax Filing Rules

Missouri also amended the regulation governing consolidated corporate income tax returns (Mo. Regs. Title 12 §10-2.045), introducing several procedural updates intended to streamline compliance for corporate groups.

The changes include updates to references governing corporate income apportionment methods and modifications to how certain consolidated filers determine interstate apportionment.

In addition, the rule eliminates the requirement to file Form MO-22, which previously served as an authorization and consent form for subsidiaries included in a consolidated Missouri return.

Other updates simplify administrative procedures by removing certain approvals that previously required the personal signature of the Director of Revenue and clarifying the use of filing extensions consistent with federal regulations.

For corporate groups operating across multiple states, these updates may reduce administrative complexity but still require careful attention to filing procedures and documentation requirements.

Missouri Clarifies Rules for Dividing Estimated Tax Payments Between Spouses

Missouri has also amended its regulation governing how estimated income tax payments and income are divided between spouses, particularly when couples file combined Missouri returns but must allocate income separately.

The updated rule provides clearer procedures for situations where spouses cannot agree on how estimated tax payments should be divided. It also coordinates the treatment of federal adjusted gross income (AGI) with other Missouri tax regulations and clarifies how separate Missouri adjusted gross incomes should be calculated for spouses filing a combined return.

The amendment also:

• Updates examples used to illustrate the allocation rules
• Clarifies how Social Security benefits should be allocated between spouses
• Addresses situations where one spouse could otherwise report negative federal adjusted gross income

These updates are intended to provide clearer administrative guidance for taxpayers and preparers when dividing income and estimated payments between current or former spouses.

Taxpayers who file combined Missouri returns but allocate income separately—particularly those navigating divorce, separation, or complex income structures—may want to review how estimated payments and income allocations are reported going forward.

Missouri Updates Temporary Storage Sales Tax Regulation

Another regulatory amendment clarifies the scope of Missouri’s temporary storage exemption for sales and use tax (Mo. Regs. Title 12 §10-113.300).

The updated regulation incorporates a Missouri Supreme Court decision involving a company that purchased computer parts and argued that those parts qualified for the temporary storage exemption. The court determined that because the company tested and certified the parts before shipping them out of state, those activities went beyond temporary storage and constituted taxable use within Missouri.

By incorporating the court’s ruling into the regulation, the Department of Revenue provides additional guidance regarding when the temporary storage exemption applies.

The rule also addresses related issues, including:

• The interaction between temporary storage and resale exemptions
• Whether sales to tax-exempt customers eliminate use-tax obligations
• The authority of the Administrative Hearing Commission in tax disputes

Companies that move inventory through Missouri for distribution—particularly manufacturers, technology companies, and distributors—should review their supply chain and inventory handling practices to determine whether activities conducted in the state could trigger use-tax obligations.

Additional guidance on Missouri sales and use tax regulations is available from the
Missouri Department of Revenue.

Expanded Sales Tax Exemption for Material Recovery Processing Plants

Missouri also updated its regulation governing the sales tax exemption for material recovery processing plants, which are facilities that process recyclable materials (Mo. Regs. Title 12 §10-111.060).

Previously, the exemption primarily applied to machinery and equipment used in these operations. The revised rule clarifies that the exemption may also apply to certain materials and supplies used in establishing, replacing, or expanding material recovery processing plants.

This clarification may provide additional guidance for businesses investing in recycling infrastructure or expanding existing material recovery operations.

Organizations in the recycling and waste management sectors should evaluate whether equipment, materials, or facility improvements may qualify for exemption under the updated rule.

Several Outdated Sales and Use Tax Rules Rescinded

In addition to the amendments described above, the Missouri Department of Revenue rescinded several older sales and use tax rules that were determined to be outdated or redundant.

These rules are: Mo. Regs. Title 12 §10-103.381, Items used or consumed by Photographers, Photofinishers and Photo Engravers; Mo. Regs. Title 12 §10-110.621, Application of Sales Tax Exemptions; Mo. Regs. Title 12 §10-110.201, Materials and Other Goods Used or Consumed in Manufacturing; Mo. Regs. Title 12 §10-111.061, Exempt Items Used or Consumed in Material Recovery Processing.

According to the Department, these topics are now covered by other rules or are no longer necessary.

What Businesses Should Do Next

While many of these regulatory changes primarily clarify existing rules, they still highlight several areas where businesses may want to review their compliance practices:

• Employers should evaluate payroll processes to ensure withholding requirements are correctly applied to remote or out-of-state employees.

Individual taxpayers and tax preparers should review updated guidance on how estimated tax payments and income are allocated between spouses when filing combined Missouri returns.

• Corporate groups should confirm that consolidated tax filing procedures reflect the updated Missouri rules.
• Manufacturers, distributors, and technology companies should review whether inventory activities conducted in Missouri could trigger use-tax obligations.
• Recycling and material recovery operations should assess whether facility investments may qualify for expanded sales tax exemptions.

Tax regulations continue to evolve, and even technical updates can affect compliance obligations. Monitoring regulatory changes and reviewing internal tax processes periodically can help organizations reduce risk and maintain compliance with state requirements.

The above updates are effective 30 days after publication in the Code of Regulations.

Businesses with questions about how these updates may apply to their operations may benefit from consulting with a tax advisor experienced in state and local tax compliance.