UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 11-K

FOR ANNUAL REPORTS OF EMPLOYEE STOCK PURCHASE, SAVINGS

AND SIMILAR PLANS PURSUANT TO SECTION 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

(Mark One)

For the fiscal year ended December 31, 2021

OR

For the transition period from                      to                     

Commission file number: 000-20827

CASS INFORMATION SYSTEMS, INC. 401(K) PLAN

CASS INFORMATION SYSTEMS, INC.

12444 Powerscourt Drive, Suite 550

St. Louis, Missouri 63131

REQUIRED INFORMATION

The Cass Information Systems, Inc. 401(k) Plan (the “Plan”) is subject to the provisions of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), and for purposes of satisfying the requirements of Form 11-K has included for filing herewith the Plan financial statements and schedule prepared in accordance with the financial reporting requirements of ERISA.

CASS INFORMATION SYSTEMS, INC. 401(K) PLAN INDEX

Armanino LLP 6 Cityplace DR Suite 900 St. Louis, MO 63141-7194 314-983-1200 main armaninoLLP.com

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Plan Administrator and Plan Participants of

Cass Information Systems, Inc. 401(K) Plan

St. Louis, Missouri

Opinion on the Financial Statements

We have audited the accompanying statements of net assets available for benefits of the Cass Information Systems, Inc. 401(k) Plan (the “Plan”) as of December 31, 2021 and 2020, and the related statements of changes in net assets available for benefits for the years then ended, and the related notes (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the net assets available for benefits of the Plan as of December 31, 2021 and 2020, and the changes in net assets available for benefits for the years then ended, in conformity with accounting principles generally accepted in the United States of America.

Basis for Opinion

These financial statements are the responsibility of the Plan’s management. Our responsibility is to express an opinion on the Plan’s financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Plan in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Plan is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. Our audits included consideration of internal control over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Plan’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Supplemental Information

The supplemental information contained in the Schedule H, Line 4i-Schedule of Assets (Held at Year End) has been subjected to audit procedures performed in conjunction with the audit of the Plan’s financial statements. The supplemental information is the responsibility of the Plan’s management. Our audit procedures included determining whether the supplemental information reconciles to the financial statements or the underlying accounting and other records, as applicable, and performing procedures to test the completeness and accuracy of the information presented in the supplemental information. In forming our opinion on the supplemental information, we evaluated whether the supplemental information, including its form and content, is presented in conformity with the Department of Labor’s Rules and Regulations for Reporting and Disclosure under the Employee Retirement Income Security Act of 1974. In our opinion, the supplemental information is fairly stated, in all material respects, in relation to the financial statements as a whole.

/s/ Armanino LLP

We have served as the Plan’s auditor since 2019.

St. Louis, Missouri

June 28, 2022

CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Statements of Assets Available for Benefits

December 31, 2021 and 2020

See accompanying notes to financial statements.

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CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Statements of Changes in Assets Available for Benefits

Years ended December 31, 2021 and 2020

See accompanying notes to financial statements.

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CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Notes to Financial Statements

NOTE 1 – PLAN DESCRIPTION

The following description of the Plan provides general information. Participants should refer to the plan document for a more complete description of the Plan’s provisions.

For all employees that are eligible to participate in the Plan but are not eligible to participate in the Company’s defined benefit retirement plan (generally starting employment at the Company subsequent to December 31, 2016), the Company provides a 3% contribution and matches 50% of the first 6% of employee contributions, subject to IRS limitations.

Prior to March 2021, for employees that participated in the Company’s defined benefit retirement plan, the Company matched 50% of the first 3% of employee contributions, subject to IRS limitations. Upon freezing future benefit accruals under the Company’s defined benefit retirement plan, all employees eligible for the Plan received the same 3% contribution and 50% of the first 6% of employee contributions match discussed above for employees not eligible to participate in the Company’s defined benefit pension plan. These longer-term employees will also receive an additional 3% contribution until a target date of December 31, 2023. The participant does not need to be actively making deferrals into the Plan to be eligible to receive the additional contribution.

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CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Notes to Financial Statements

If an employee terminates employment before full vesting, the nonvested portions of employer matching and discretionary contributions are used to reduce future contributions or plan administration costs of the Company. At December 31, 2021 and 2020, the forfeited nonvested accounts had zero balances. Employer contributions were reduced from forfeited nonvested accounts by $288,518 and $138,317 during 2021 and 2020, respectively.

NOTE 2 – SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

The following are the significant accounting policies followed by the Plan:

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CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Notes to Financial Statements

Purchases and sales of securities are recorded on a trade-date basis. Interest income is recorded on the accrual basis. Dividends are recorded on the ex-dividend date. Net appreciation includes the Plan’s gains and losses on investments bought and sold as well as held during the year.

NOTE 3 – FAIR VALUE MEASUREMENTS

The Plan’s investments are reported at fair value in the accompanying statements of assets available for benefits. The methods used to measure fair value may produce an amount that may not be indicative of net realizable value or reflective of future values. Furthermore, although the Plan Administrator believes the valuation methods are appropriate and consistent with other market participants, the use of different methodologies or assumptions to determine the fair value of certain financial instruments could result in a different fair value measurement at the reporting date.

The fair value measurement accounting literature establishes a value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. This hierarchy consists of three broad levels:

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CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Notes to Financial Statements

Level 1 – Inputs to the valuation methodology are unadjusted quoted prices for identical assets and liabilities in active markets and have the highest priority.

Level 2 – Inputs to the valuation methodology include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in inactive markets, inputs other than quoted prices that are observable for the asset or liability, or inputs that are derived principally from or corroborated by observable market data by correlation or other means. If the asset or liability has a specified (contractual) term, the Level 2 input must be observable for substantially the full term of the asset or liability.

Level 3 – Inputs to the valuation methodology are unobservable and have the lowest priority.

The Plan uses appropriate valuation techniques based on the available inputs to measure the fair value of its investments. When available, the Plan measures fair value using Level 1 inputs because they generally provide the most reliable evidence of fair value. Level 3 inputs are used only when Level 1 and Level 2 inputs are not available.

Following is a description of the valuation methodologies used for assets measured at fair value. There have been no changes in the methodologies used at December 31, 2021 and 2020.

Common stocks – valued at the closing price reported on the active market on which the individual securities are traded (Level 1 inputs).

Mutual funds – valued at the daily closing price as reported by the fund (Level 1 inputs). Mutual funds held by the Plan are open-end mutual funds which are registered with the Securities and Exchange Commission. These funds are required to publish their daily net asset value (NAV) and to transact at that price. The mutual funds held by the Plan are deemed to be actively traded.

Collective trust funds – valued at the NAV of the units of the Principal Trust Company collective trusts. The NAV, as provided by the trustee, is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by the fund less its liabilities. The investments have no unfunded commitments and can be redeemed daily with a one day notice period.

Pooled separate accounts – valued at the NAV of the pooled separate accounts. The NAV, as provided by the Trustee, is used as a practical expedient to estimate fair value. The NAV is based on the fair value of the underlying investments held by the fund less its liabilities. The investments have no unfunded commitments and can be redeemed daily with a one day notice period.

Insurance company general account contracts – fair value is the amount the Plan’s participants would receive currently if they were to withdraw or transfer funds from the Plan prior to their maturity for an event other than death, disability, termination, or retirement. This fair value represents contract value adjusted to reflect current market interest rates only to the extent such market rates exceed crediting rates (Level 3 inputs).

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CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Notes to Financial Statements

The following tables set forth, by level with the fair value hierarchy, the Plan’s investments at fair value as of December 31, 2021 and 2020:

Following is a summary of changes in the fair value of the insurance company general account, the only plan asset valued using Level 3 inputs, for the years ended December 31, 2021 and 2020:

NOTE 4 – RELATED PARTY TRANSACTIONS

Certain Plan investments are units of insurance company general account product, pooled accounts or collective trust funds managed by Principal Life Insurance Company or affiliates thereof. Principal Life Insurance Company is the Trustee as defined by the Plan and, therefore, these

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CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Notes to Financial Statements

transactions qualify as party-in-interest transactions. Fees paid by the Plan for the investment management and recordkeeping services amounted to $28,263 and $21,948 for the years ended December 31, 2021 and 2020, respectively.

The Plan invests in common stock of the Company. At December 31, 2021 and 2020, the Plan held 24,948 and 24,033 shares of Company common stock, with fair values of $980,966 and $935,129, respectively. During the years ended December 31, 2021 and 2020, the Plan received cash and stock dividends totaling $27,279 and $24,924, respectively, on shares of Company common stock.

NOTE 5 – PLAN TERMINATION

Although it has not expressed any intent to do so, the Plan Administrator has the right under the Plan to terminate the Plan subject to the provisions set forth in ERISA. In the event of plan termination, participants become 100% vested in their accounts. The Company may elect to have all assets transferred to another qualified plan in which all participants who would have otherwise received a distribution will have an interest, and each person’s interest will be nonforfeitable as to amounts attributable to assets transferred on his or her behalf.

NOTE 6 – RISKS AND UNCERTAINTIES

The Plan invests in various investment securities. Investment securities are exposed to various risks such as interest rate, market, and credit risks. Due to the level of risk associated with certain investment securities, it is at least reasonably possible that changes in the values of investment securities will occur in the near term and that such changes could materially affect participants’ account balances and the amounts reported in the statements of assets available for benefits.

NOTE 7 – FEDERAL INCOME TAXES

The Internal Revenue Service issued its latest determination letter on August 8, 2014, which indicates the prototype plan document adopted by the Plan qualifies under the provisions of Section 401(a) and the trust is exempt from federal income taxes under the provisions of Section 501(a) of the Internal Revenue Code, as amended. While various amendments have been made to the Plan since 2014, in the opinion of the Plan Administrator, the Plan and its underlying trust have operated within the terms of the Plan and remain qualified under the applicable provisions of the Internal Revenue Code.

NOTE 8 – RECONCILIATION OF FINANCIAL STATEMENTS TO FORM 5500

The following is a reconciliation of the financial statements at December 31, 2021 and for the year ended December 31, 2021 to the Form 5500:

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Schedule

CASS INFORMATION SYSTEMS, INC.

401(k) PLAN

Employer Identification Number: 43-1265338

Plan Number: 002

Schedule H, line 4i – Schedule of Assets (Held at End of Year)

December 31, 2021

See accompanying report of independent registered public accounting firm.

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EXHIBIT INDEX

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SIGNATURES

The Plan. Pursuant to the requirements of the Securities Exchange Act of 1934, the trustees (or other person who administer the employee benefit plan) have duly caused this annual report to be signed on its behalf by the undersigned hereunto duly authorized.

Date: June 28, 2022

Exhibit 23.1

Consent of Independent Registered Public Accounting Firm

We consent to incorporation by reference in the Registration Statement (Form S-8 No. 333-181772) of Cass Information Systems, Inc. of our report dated June 28, 2022, relating to our audit of the Cass Information Systems, Inc. 401(K) Plan financial statements and the related supplemental Schedule of Assets (Held at End of Year) which appears in this Annual Report on Form 11-K of the Cass Information Systems, Inc. 401(K) Plan for the year ended December 31, 2021.

/s/ Armanino LLP

St. Louis, Missouri

June 28, 2022