Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements of the Company were prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim consolidated financial information, general practices within the banking industry and with instructions for Form 10-Q and Regulation S-X. Accordingly, these interim financial statements do not include all the information or footnotes required by U.S. GAAP for annual financial statements. However, in the opinion of management, all adjustments (consisting solely of normal recurring adjustments) necessary for a fair presentation of these consolidated financial statements have been included. The results of operations for the interim periods disclosed herein are not necessarily indicative of the results which may be expected for the entire year. These statements should be read in conjunction with the audited consolidated financial statements and notes thereto contained in the Annual Report on Form 10-K for the fiscal year ended December 31, 2025, as filed with the U.S. Securities and Exchange Commission (“SEC”) on March 20, 2026, and as amended by Form 10-K/A as filed with the SEC on April 30, 2026.
Corporate Structure	Corporate Structure The Bank offers a full range of banking and investment management services to its customers. The Bank focuses on four core services that center around customer needs. The core services include residential lending, commercial banking, personal banking and wealth management. The Bank offers a full range of commercial and consumer banking services through its network of five full-service branch locations. Investment management services are offered through FSB Wealth Management - a division of First Seacoast Bank. FSB Wealth Management provides access to non-FDIC insured products that include retirement planning, portfolio management, investment and insurance strategies, business retirement plans and college planning to individuals throughout our primary market area. These investments and services are offered through a third-party registered broker-dealer and investment advisor. FSB Wealth Management receives fees from advisory services and commissions on individual investment and insurance products purchased by clients. The assets held for wealth management customers are not assets of the Company and, accordingly, are not reflected in the Company’s consolidated balance sheets. The Bank is engaged principally in the business of attracting deposits from the public and investing those funds in various types of loans, including residential and commercial real estate loans, and a variety of commercial and consumer loans. The Bank also invests its deposits and borrowed funds in investment securities. Deposits at the Bank are insured by the Federal Deposit Insurance Corporation (“FDIC”) for the maximum amount permitted by law. The Company has one reportable segment, “Banking Services.” All of the Company’s activities are interrelated, and each activity is dependent and assessed based on how each of the activities of the Company supports the others. For example, lending is dependent upon the ability of the Company to fund itself with deposits and other borrowings and manage interest rate and credit risk. Accordingly, all significant operating decisions are based upon analysis of the Company as one segment or unit. The Company adopted Accounting Standards Update ("ASU") 2023-07, “Segment Reporting (Topic 280) - Improvements to Reportable Segment Disclosures," on January 1, 2024, which provides updated guidance for segment reporting. The Company has determined that all of its banking services meet the aggregation criteria of ASC 280, Segment Reporting, as its current operating model is structured whereby the Bank serves a similar base of customers who utilize a company-wide offering of similar products and services managed through similar processes that are collectively reviewed by the Company’s Chief Executive Officer, who has been identified as the chief operating decision maker (“CODM”). The CODM regularly assesses performance of the aggregated single operating and reporting segment and decides how to allocate resources based upon net income or loss calculated on the same basis as net income or loss is reported in the Company’s consolidated statements of net loss and other comprehensive loss. The CODM is also regularly provided with the expense information at a level consistent with that disclosed in the Company’s consolidated statements of loss and of other comprehensive loss.
Recent Accounting Pronouncements Yet to be Adopted	Recent Accounting Pronouncements Yet To Be Adopted The Company considers the applicability and impact of all ASUs. ASUs not listed below were assessed and determined to be either not applicable or are expected to have an immaterial impact on the Company’s consolidated financial statements. In November 2025, the FASB issued ASU 2025-08, “Financial Instruments - Credit Losses (Topic 326): Purchased Loans.” ASU 2025-08 amends the guidance in ASC 326 on the accounting for certain purchased loans. Under the ASU, entities must account for acquired loans that meet certain criteria at acquisition (“purchased seasoned loans”) by recognizing the loan at its purchase price plus an allowance for expected credit losses (i.e., the gross-up approach). The ASU’s amendments align the accounting for purchased seasoned loans with the treatment of financial assets purchased with more-than-insignificant credit deterioration since origination (“PCD assets”). ASU 2025-08 is effective for annual reporting periods beginning after December 15, 2026 on a prospective basis. Early adoption is also permitted. We are currently evaluating the effect this standard will have on our consolidated financial statements. In November 2024, the FASB issued ASU 2024-03, “Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures.” ASU 2024-03 requires disaggregated disclosure of income statement expenses for public business entities. ASU 2024-03 requires new financial statement disclosures in tabular format, disaggregating information about prescribed categories underlying any relevant income statement expense caption. The prescribed categories include, among other things, employee compensation, depreciation, and intangible asset amortization. Additionally, entities must disclose the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. ASU 2024-03 is effective for annual reporting periods beginning after December 15, 2026 on a prospective basis. Retrospective application for all periods presented is permitted. Early adoption is also permitted. We are currently evaluating the effect this standard will have on our disclosures. Recently Adopted Accounting Pronouncements In December 2023, the FASB issued ASU 2023-09, "Income Taxes- Improvements to Income Tax Disclosures", which requires enhancements and further transparency to various income tax disclosures, most notably the tax rate reconciliation and income taxes paid. ASU 2023-09 became effective for annual periods beginning after December 15, 2024 on a prospective basis. Retrospective application for all periods presented is permitted. Early adoption was also permitted. ASU 2023-09 did not have a material impact on the Company's consolidated financial statements.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2026

The accompanying unaudited consolidated financial statements of the Company were prepared in accordance with generally accepted accounting principles in the United States of America (“U.S. GAAP”) for interim consolidated financial information, general practices within the banking industry and with instructions for Form 10-Q and Regulation S-X. Accordingly, these interim financial statements do not include all the information or footnotes required by U.S. GAAP for annual financial statements. However, in the opinion of management, all adjustments (consisting solely of normal recurring adjustments) necessary for a fair presentation of these consolidated financial statements have been included. The results of operations for the interim periods disclosed herein are not necessarily indicative of the results which may be expected for the entire year. These statements should be read in conjunction with the audited consolidated financial statements and notes thereto contained in the Annual Report on Form 10-K for the fiscal year ended December 31, 2025, as filed with the U.S. Securities and Exchange Commission (“SEC”) on March 20, 2026, and as amended by Form 10-K/A as filed with the SEC on April 30, 2026.

Corporate Structure

The Bank offers a full range of banking and investment management services to its customers. The Bank focuses on four core services that center around customer needs. The core services include residential lending, commercial banking, personal banking and wealth management. The Bank offers a full range of commercial and consumer banking services through its network of five full-service branch locations. Investment management services are offered through FSB Wealth Management - a division of First Seacoast Bank. FSB Wealth Management provides access to non-FDIC insured products that include retirement planning, portfolio management, investment and insurance strategies, business retirement plans and college planning to individuals throughout our primary market area. These investments and services are offered through a third-party registered broker-dealer and investment advisor. FSB Wealth Management receives fees from advisory services and commissions on individual investment and insurance products purchased by clients. The assets held for wealth management customers are not assets of the Company and, accordingly, are not reflected in the Company’s consolidated balance sheets.

The Bank is engaged principally in the business of attracting deposits from the public and investing those funds in various types of loans, including residential and commercial real estate loans, and a variety of commercial and consumer loans. The Bank also invests its deposits and borrowed funds in investment securities. Deposits at the Bank are insured by the Federal Deposit Insurance Corporation (“FDIC”) for the maximum amount permitted by law.

The Company has one reportable segment, “Banking Services.” All of the Company’s activities are interrelated, and each activity is dependent and assessed based on how each of the activities of the Company supports the others. For example, lending is dependent upon the ability of the Company to fund itself with deposits and other borrowings and manage interest rate and credit risk. Accordingly, all significant operating decisions are based upon analysis of the Company as one segment or unit.

The Company adopted Accounting Standards Update ("ASU") 2023-07, “Segment Reporting (Topic 280) - Improvements to Reportable Segment Disclosures," on January 1, 2024, which provides updated guidance for segment reporting. The Company has determined that all of its banking services meet the aggregation criteria of ASC 280, Segment Reporting, as its current operating model is structured whereby the Bank serves a similar base of customers who utilize a company-wide offering of similar products and services managed through similar processes that are collectively reviewed by the Company’s Chief Executive Officer, who has been identified as the chief operating decision maker (“CODM”).

The CODM regularly assesses performance of the aggregated single operating and reporting segment and decides how to allocate resources based upon net income or loss calculated on the same basis as net income or loss is reported in the Company’s

consolidated statements of net loss and other comprehensive loss. The CODM is also regularly provided with the expense information at a level consistent with that disclosed in the Company’s consolidated statements of loss and of other comprehensive loss.

Recent Accounting Pronouncements Yet to be Adopted

Recent Accounting Pronouncements Yet To Be Adopted

The Company considers the applicability and impact of all ASUs. ASUs not listed below were assessed and determined to be either not applicable or are expected to have an immaterial impact on the Company’s consolidated financial statements.

In November 2025, the FASB issued ASU 2025-08, “Financial Instruments - Credit Losses (Topic 326): Purchased Loans.” ASU 2025-08 amends the guidance in ASC 326 on the accounting for certain purchased loans. Under the ASU, entities must account for acquired loans that meet certain criteria at acquisition (“purchased seasoned loans”) by recognizing the loan at its purchase price plus an allowance for expected credit losses (i.e., the gross-up approach). The ASU’s amendments align the accounting for purchased seasoned loans with the treatment of financial assets purchased with more-than-insignificant credit deterioration since origination (“PCD assets”). ASU 2025-08 is effective for annual reporting periods beginning after December 15, 2026 on a prospective basis. Early adoption is also permitted. We are currently evaluating the effect this standard will have on our consolidated financial statements.

In November 2024, the FASB issued ASU 2024-03, “Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures.” ASU 2024-03 requires disaggregated disclosure of income statement expenses for public business entities. ASU 2024-03 requires new financial statement disclosures in tabular format, disaggregating information about prescribed categories underlying any relevant income statement expense caption. The prescribed categories include, among other things, employee compensation, depreciation, and intangible asset amortization. Additionally, entities must disclose the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. ASU 2024-03 is effective for annual reporting periods beginning after December 15, 2026 on a prospective basis. Retrospective application for all periods presented is permitted. Early adoption is also permitted. We are currently evaluating the effect this standard will have on our disclosures.

Recently Adopted Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, "Income Taxes- Improvements to Income Tax Disclosures", which requires enhancements and further transparency to various income tax disclosures, most notably the tax rate reconciliation and income taxes paid. ASU 2023-09 became effective for annual periods beginning after December 15, 2024 on a prospective basis. Retrospective application for all periods presented is permitted. Early adoption was also permitted. ASU 2023-09 did not have a material impact on the Company's consolidated financial statements.