MO-MSS: S Corporation Allocation and Apportionment Form and Instructions (2024)

Who files this form

S corporations use Form MO-MSS to allocate and apportion income using the Receipts Factor Apportionment Method or another appropriate method. Attach it to Form MO-1120S.

A taxpayer must have income from more than one state to allocate and apportion income. Do not complete this form if all income is from Missouri sources.

Corporations defined as broadcasters under 12 CSR 10-2.260 must choose Method Seven.

What you'll need

Have the following information and forms ready:

• Corporation name, Missouri tax identification number, charter number, federal employer identification number, and taxable year beginning and ending dates.
• Form MO-1120S, which receives the MO-MSS attachment, and Form MO-NRS, where the calculated percentages are entered.
• Missouri receipts and total receipts everywhere for the Receipts Factor Apportionment Method.
• Missouri miles and total miles for Methods Three through Six, if applicable.
• Gross income and related expenses, both everywhere and in Missouri, for any nonapportionable income being allocated.
• Partnership apportionment factors and the corporation’s ownership percentage, if the corporation owns an interest in a partnership.

Additional attachments may be required:

• An explanation and computations supporting nonapportionable income, plus a similar table for any distributive share item not listed on the form.
• A detailed explanation for special Methods Three through Seven.
• For Method Seven, either an approval letter or an explanation identifying the authorizing Missouri regulation and why the corporation qualifies.
• A detailed statement explaining any reasonable approximation used when the state assignment of receipts cannot be determined.

How to file

1. Enter the corporation’s identifying information and taxable year dates. Select only one apportionment method.
2. For Method Two A, complete Part 1, Lines 1 through 3. Divide Missouri receipts on Line 1 by total receipts everywhere on Line 2 to calculate the receipts factor on Line 3.
3. Transfer the percentage to Form MO-NRS as directed. A distributive share item with nonapportionable income may require a different percentage, calculated using the steps on MO-MSS.
4. Complete Lines 4 through 10 if there is nonapportionable income to allocate. Include the required explanations, computations, and additional tables.
5. For a special method, follow that method’s directions and attach the required explanation.
6. Attach Form MO-MSS to Form MO-1120S and mail it to the Missouri Department of Revenue.

For a refund or no amount due, the printed mailing address is:

P.O. Box 336

Jefferson City, MO 65105-0336

Common mistakes

• Completing MO-MSS when all income is from Missouri sources. The form says not to complete it in that situation.
• Selecting more than one method. Select only one apportionment election box.
• Treating income as nonapportionable without support. All income is presumed apportionable unless you can clearly show otherwise. Labels such as interest, dividends, rents, or royalties do not settle the classification.
• Allocating excluded expenses. Do not allocate expenses that have been excluded from federal taxable income.
• Including prohibited receipts in the receipts factor. Receipts from hedging transactions or from the maturity, redemption, sale, exchange, loan, or other disposition of cash or securities must not be included in either the numerator or denominator.
• Using Method Seven without authorization or required attachments. It requires prior approval or an authorizing Missouri regulation, along with the required explanation and approval documentation.

Questions people ask

How is the receipts factor calculated?

Divide Missouri receipts on Part 1, Line 1 by total receipts everywhere on Line 2. Enter the result on Line 3 and transfer the percentage to Form MO-NRS as directed.

What if the corporation owns part of a partnership?

Multiply the partnership’s factors by the corporation’s ownership percentage, then add those amounts to the corporation’s apportionment factors.

Does each distributive share item use the same percentage?

Not necessarily. If an item is wholly or partly allocated as nonapportionable income, calculate a separate percentage for that item using the steps on Form MO-MSS.

What if I cannot determine which state receives the receipts?

Reasonably approximate the state or states to which the receipts should be assigned. Attach a detailed statement explaining the basis for the approximation.

Official sources

• https://dor.mo.gov/forms/MO-MSS_2024.pdf