Description of Business and Summary of Significant Accounting Policies	6 Months Ended
Jun. 30, 2025
Accounting Policies [Abstract]
Description of Business and Summary of Significant Accounting Policies	Description of Business and Summary of Significant Accounting Policies Nature of operations - Coastal Financial Corporation (“Corporation” or “Company”) is a registered bank holding company whose wholly owned subsidiaries are Coastal Community Bank (“Bank”) and Arlington Olympic LLC (“LLC”). The Company is a Washington state corporation that was organized in 2003. The Bank was incorporated and commenced operations in 1997 and is a Washington state-chartered commercial bank that is a member bank of the Federal Reserve system. The LLC was formed in 2019 and owns the Company’s Arlington branch site, which the Bank leases from the LLC. The Company operates through the Bank and is headquartered in Everett, Washington, which by population is the largest city in Snohomish County. The Company’s business is conducted through three reportable segments: The community bank, CCBX and treasury & administration. The primary focus of the community bank is on providing a wide range of banking products and services to consumers and small to medium sized businesses in the broader Puget Sound region in the state of Washington and through the Internet and our mobile banking application. We currently operate 14 full-service banking locations, 12 of which are located in Snohomish County, where we are the largest community bank by deposit market share, and two of which are located in neighboring counties (one in King County and one in Island County). The CCBX segment provides banking as a service (“BaaS”) that allows digital financial service providers, companies and brands to offer their customers banking services. The CCBX segment had a total of 29 partners, at varying stages, as of June 30, 2025. The treasury & administration segment includes investments, debt and other reporting items that are not specific to the community bank or CCBX segments. The Bank’s deposits are insured in whole or in part by the Federal Deposit Insurance Corporation (“FDIC”). The community bank’s loans and deposits are primarily within the greater Puget Sound region, while CCBX loans and deposits are dependent upon the partner’s market. The Bank’s primary funding source is deposits from customers. The Bank is subject to regulation and supervision by the Board of Governors of the Federal Reserve System and the Washington State Department of Financial Institutions Division of Banks. The Federal Reserve also has regulatory and supervisory authority over the Company. Financial statement presentation - The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim reporting requirements and with instructions to Form 10-Q and Article 10 of Regulation S-X, and therefore do not include all the information and notes included in the annual consolidated financial statements in conformity with GAAP. These interim condensed consolidated financial statements and accompanying notes should be read in conjunction with the Company’s audited consolidated financial statements and accompanying notes included in the Company’s Annual report on Form 10-K as filed with the U.S. Securities and Exchange Commission (“SEC”) on March 17, 2025. Operating results for the three and six months ended June 30, 2025 are not necessarily indicative of the results that may be expected for the entire year. Amounts presented in the consolidated financial statements and footnote tables are rounded and presented in thousands of dollars except per-share amounts, which are presented in dollars. In the narrative footnote discussion, amounts are rounded to thousands and presented in dollars. In management’s opinion, all accounting adjustments necessary to accurately reflect the financial position and results of operations on the accompanying consolidated financial statements have been made. These adjustments include normal and recurring accruals considered necessary for a fair and accurate presentation. Principles of consolidation - The consolidated financial statements include the accounts of the Company, the Bank and the LLC. All significant intercompany accounts have been eliminated in consolidation. Estimates - The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management believes that its critical accounting policies include determining the allowance for credit losses, the valuation of the Company’s deferred tax assets, and fair value of financial instruments. Actual results could differ significantly from those estimates. Subsequent Events - The Company has evaluated events and transactions subsequent to June 30, 2025 for potential recognition or disclosure. Reclassifications - Certain amounts reported in prior quarters' consolidated financial statements may have been reclassified to conform to the current presentation with no effect on stockholders’ equity or net income.

Nature of operations - Coastal Financial Corporation (“Corporation” or “Company”) is a registered bank holding company whose wholly owned subsidiaries are Coastal Community Bank (“Bank”) and Arlington Olympic LLC (“LLC”). The Company is a Washington state corporation that was organized in 2003. The Bank was incorporated and commenced operations in 1997 and is a Washington state-chartered commercial bank that is a member bank of the Federal Reserve system. The LLC was formed in 2019 and owns the Company’s Arlington branch site, which the Bank leases from the LLC.

The Company operates through the Bank and is headquartered in Everett, Washington, which by population is the largest city in Snohomish County. The Company’s business is conducted through three reportable segments: The community bank, CCBX and treasury & administration. The primary focus of the community bank is on providing a wide range of banking products and services to consumers and small to medium sized businesses in the broader Puget Sound region in the state of Washington and through the Internet and our mobile banking application. We currently operate 14 full-service banking locations, 12 of which are located in Snohomish County, where we are the largest community bank by deposit market share, and two of which are located in neighboring counties (one in King County and one in Island County). The CCBX segment provides banking as a service (“BaaS”) that allows digital financial service providers, companies and brands to offer their customers banking services. The CCBX segment had a total of 29 partners, at varying stages, as of June 30, 2025. The treasury & administration segment includes investments, debt and other reporting items that are not specific to the community bank or CCBX segments.

The Bank’s deposits are insured in whole or in part by the Federal Deposit Insurance Corporation (“FDIC”). The community bank’s loans and deposits are primarily within the greater Puget Sound region, while CCBX loans and deposits are dependent upon the partner’s market. The Bank’s primary funding source is deposits from customers. The Bank is subject to regulation and supervision by the Board of Governors of the Federal Reserve System and the Washington State Department of Financial Institutions Division of Banks. The Federal Reserve also has regulatory and supervisory authority over the Company.

Financial statement presentation - The accompanying unaudited interim condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim reporting requirements and with instructions to Form 10-Q and Article 10 of Regulation S-X, and therefore do not include all the information and notes included in the annual consolidated financial statements in conformity with GAAP. These interim condensed consolidated financial statements and accompanying notes should be read in conjunction with the Company’s audited consolidated financial statements and accompanying notes included in the Company’s Annual report on Form 10-K as filed with the U.S. Securities and Exchange Commission (“SEC”) on March 17, 2025. Operating results for the three and six months ended June 30, 2025 are not necessarily indicative of the results that may be expected for the entire year.

Amounts presented in the consolidated financial statements and footnote tables are rounded and presented in thousands of dollars except per-share amounts, which are presented in dollars. In the narrative footnote discussion, amounts are rounded to thousands and presented in dollars.

In management’s opinion, all accounting adjustments necessary to accurately reflect the financial position and results of operations on the accompanying consolidated financial statements have been made. These adjustments include normal and recurring accruals considered necessary for a fair and accurate presentation.

Estimates - The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Management believes that its critical accounting policies include determining the allowance for credit losses, the valuation of the Company’s deferred tax assets, and fair value of financial instruments. Actual results could differ significantly from those estimates.