What Is Kansas Form K-120S and How Do I File?

Form K-120S is the Kansas S Corporation Income Tax Return, used by S corporations doing business in the state to report their annual income, deductions, and credits. As a pass-through entity, an S corporation generally does not pay income tax itself. Instead, its profits and losses are “passed through” to the individual shareholders, who then report this information on their personal state income tax returns. The K-120S form allows Kansas to track income attributable to the state and verify that shareholders are correctly reporting their portion.

Determining Filing Obligations

An S corporation must file Form K-120S if it is organized under Kansas law or derives any income from Kansas sources, even if its activities are minimal. For corporations on a calendar year, the due date for the K-120S is April 15th. If the corporation uses a fiscal year for its accounting, the return is due by the 15th day of the fourth month after its fiscal year closes.

Kansas recognizes federal extensions. If a corporation files for a federal extension with Form 7004, an extension for the K-120S is automatically granted. This is an extension to file, not to pay. Any anticipated tax must be paid by the original due date to avoid penalties and interest.

Required Information and Key Calculations

A corporation must have its completed federal income tax return, Form 1120-S, as the Kansas return starts with information from the federal form. You will need detailed information for every shareholder, including their full name, address, Social Security Number or Employer Identification Number, and their ownership percentage. A complete year-end balance sheet that matches the one from the federal return is also necessary.

A calculation for corporations with operations both inside and outside of Kansas is the apportionment of business income. Kansas utilizes a three-factor apportionment formula based on property, payroll, and sales. This percentage determines the portion of the corporation’s business income subject to Kansas tax. For tax years beginning on or after January 1, 2027, the state will transition to a single-sales factor apportionment formula.

Certain situations can trigger an entity-level tax. A tax on built-in gains can apply if a former C corporation sells assets that appreciated in value before the S corporation election. Additionally, an S corporation may elect to pay tax on behalf of its shareholders by indicating the election on Form K-120S.

Filing the Return and Distributing Schedules

The completed K-120S can be filed electronically through the Kansas Department of Revenue’s online portal or by using approved tax preparation software. To file by mail, the completed return should be sent to the address specified in the form’s instructions.

If there is a tax liability, such as from built-in gains, payment can be made electronically or by mail. When paying by mail, a payment voucher, Form K-120V, must be included with the check or money order. Electronic payments can be made directly on the Department of Revenue’s website.

The corporation must provide each shareholder with a completed Schedule K-1, which details their specific share of the corporation’s income, deductions, and credits as apportioned to Kansas. If the corporation elected to pay tax on behalf of its shareholders, it must also provide each shareholder with Form K-9, which reports the tax paid. These documents must be furnished to every shareholder by the due date of the K-120S return, including extensions.

How Shareholders Use the Schedule K-1

The Schedule K-1 received from the S corporation contains the specific figures the shareholder needs to report on their personal Kansas income tax return, Form K-40. The data from the K-1 links the S corporation’s activity to the shareholder’s individual tax liability. When preparing their return, shareholders use the information from Schedule K-1 to report their share of Kansas income or loss. If the S corporation paid tax on the shareholder’s behalf, the shareholder uses the information from Form K-9 to claim a credit for taxes paid on their Form K-40.