Significant Accounting Policies (Policies)	9 Months Ended
Significant Accounting Policies (Policies)	Sep. 30, 2025
SIGNIFICANT ACCOUNTING POLICIES [Abstract]
Basis of Presentation	Basis of Presentation The Company’s financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”). The Company is an investment company following the accounting and reporting requirements set forth in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 946, Financial Services—Investment Companies ("ASC 946") and Articles 6 and 12 of Regulation S-X. The financial statements reflect all adjustments and reclassification that, in the opinion of management, are necessary for the fair statement of results of operations and financial condition as of and for the periods presented. The current period’s results of operations are not necessarily indicative of results that may be achieved for the full fiscal year.
Consolidation	Consolidation As provided under ASC 946, the Company will not consolidate its investment in a portfolio company other than an investment company subsidiary or a controlled operating company whose business consists of providing services to the Company. An investment company’s interests in portfolio companies that are not investment companies are measured at fair value in accordance with ASC 946.
Reclassifications	Reclassifications Certain reclassifications have been made in the presentation of prior year financial statements and accompanying notes to conform to the current period presentation.
Use of Estimates	Use of Estimates The preparation of the financial statements in conformity with U.S. GAAP requires management to make certain estimates and assumptions affecting reported amounts of assets and liabilities at the date of the financial statements and the reported amounts of income, expenses, and gains and losses during the reported period. These estimates are based on the information that is currently available to the Company and on various other assumptions that the Company believes to be reasonable under the circumstances. Actual results could differ materially from those estimates under different assumptions and conditions.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consists of funds deposited with financial institutions and short-term (maturity of 90 days or less) liquid investments and money market funds. Funds held in money market funds are considered Level 1 in the fair value hierarchy in accordance with ASC 820, Fair Value Measurement ("ASC 820"). Cash held in demand deposit accounts may exceed the Federal Deposit Insurance Corporation (“FDIC”) insured limit. The Company has not incurred any losses on these accounts, and the credit risk exposure is mitigated by the financial strength of the banking institution where the accounts are held. As of September 30, 2025 and December 31, 2024, cash and cash equivalents consisted of $10.5 million and $23.9 million, respectively, all of which are held with high credit quality financial institutions, which are members of the FDIC.
Investment Transactions	Investment Transactions Investment transactions are recorded on the trade date. Realized gains or losses are recognized as the difference between the net proceeds received (excluding prepayment fees, if any) and the amortized cost basis of the investment using the specific identification method without regard to unrealized gains or losses previously recognized, and include investments written off during the period, net of recoveries. Current-period changes in the fair value of investments are reflected as a component of the net change in unrealized appreciation (depreciation) from investments on the Statements of Operations. The net change in unrealized appreciation (depreciation) primarily reflects the change in fair value of investments as of the last business day of the reporting period, including the reversal of previously recorded unrealized gains or losses with respect to investments realized during the period. Investments traded but not yet settled, if any, are reported in payable for investments purchased and receivable for investments sold on the Statements of Assets and Liabilities.
Investment Valuation	Investment Valuation The Company’s investments are recorded at their estimated fair value on the Statements of Assets and Liabilities. Investments for which market quotations are readily available will typically be valued at the bid price of those market quotations. To validate market quotations, the Adviser utilizes a number of factors to determine if the quotations are representative of fair value, including the source and number of the quotations. Debt and equity securities that are not publicly traded or whose market prices are not readily available are valued at fair value as determined in good faith by the Adviser, as the Company’s valuation designee (the “Valuation Designee”), based on inputs that may include valuations, or ranges of valuations, provided by independent third-party valuation firm(s) engaged by the Adviser. Generally, the valuation approach used for debt investments is the income approach. The approach derives a value based on either determining the present value of a projected level of cash flow, including a terminal value, or by the capitalization of a normalized measure of future cash flow. The discounted cash flow (“DCF”) method, one of the methodologies under the income approach, involves estimating future cash flows under various scenarios and discounting them to the measurement date. The discount rate represents a return required by a market participant in order to make an investment in the subject company. Alternatively, the market approach or asset approach may be used. The market approach is a way of determining a value indication by using one or more methods that compare the portfolio company to similar businesses. Value indicators are applied to relevant financial information of the entity being valued to estimate its fair value. There are two methodologies to consider under the market approach: the guideline public company method (“GPC”) and the controlling transaction method (“CTM”). The GPC method is based on the premise that the pricing multiples of comparable publicly traded companies can be used as a tool to value privately held companies. The publicly traded companies’ ratios and business enterprise value provide guidance in the valuation process. Considerations of factors such as size, growth, profitability and return on investment are also analyzed and compared to the subject business. The CTM is based on the same premise as the GPC. Guideline transactions include change-of-control transactions involving public or private businesses for companies engaged in similar lines of business or with similar economic characteristics. The valuation considers the price at which the merger or acquisition took place to other factors in order to create a pricing multiple that can be used to determine an estimate of value for the subject company. The asset approach provides an indication of the portfolio company’s value by developing a valuation-based balance sheet. This approach requires adjusting the historical assets and liabilities listed on the U.S. GAAP-based balance sheet to estimated fair values. The excess of assets over liabilities represents the tangible value of the business enterprise. The asset approach does not consider the relevant earnings capacity of a going concern business. Pursuant to Rule 2a-5 under the 1940 Act, the Board of Directors of the Company (the "Board") designated the Adviser as the Valuation Designee to perform the fair value determinations for the Company, subject to the oversight of the Board and certain Board reporting and other requirements. As part of the valuation process, the Adviser takes into account relevant factors in determining the fair value of our investments, including: the estimated enterprise value of a portfolio company (i.e., the total fair value of the portfolio company’s debt and equity), the nature and realizable value of any collateral, the portfolio company’s ability to make payments based on its earnings and cash flow, the markets in which the portfolio company does business, a comparison of the portfolio company’s securities to any similar publicly traded securities, and overall changes in the interest rate environment and the credit markets. When an external event such as a purchase transaction, public offering or subsequent equity sale occurs, the Adviser considers whether the pricing indicated by the external event corroborates its valuation. The Adviser undertakes a multi-step valuation process, which includes, among other procedures, the following: • With respect to investments for which market quotations are readily available, those investments will typically be valued at the bid price of those market quotations; • With respect to investments for which market quotations are not readily available, the valuation process begins with the Adviser’s valuation committee establishing a preliminary valuation of each investment, which may be based on valuations, or ranges of valuations, provided by independent valuation firm(s); • Preliminary valuations are documented and discussed by the Adviser’s valuation committee and, where appropriate, the independent valuation firm(s); and • The Adviser determines the fair value of each investment. We conduct this valuation process on a quarterly basis. We apply ASC 820, which establishes a framework for measuring fair value in accordance with U.S. GAAP and required disclosures of fair value measurements. ASC 820 determines fair value to be the price that would be received for an investment in a current sale, which assumes an orderly transaction between market participants on the measurement date. Market participants are defined as buyers and sellers in the principal or most advantageous market (which may be a hypothetical market) that are independent, knowledgeable, and willing and able to transact. In accordance with ASC 820, we consider the principal market to be the market that has the greatest volume and level of activity. ASC 820 specifies a fair value hierarchy that prioritizes and ranks the level of observability of inputs used in determination of fair value. In accordance with ASC 820, these levels are summarized below: • Level 1 – Valuations based on quoted prices in active markets for identical assets or liabilities that we have the ability to access at the measurement date; • Level 2 – Valuations based on quoted prices for similar assets or liabilities in active markets, or quoted prices for identical or similar assets or liabilities in markets that are not active, or for which all significant inputs are observable, either directly or indirectly; and • Level 3 – Valuations based on inputs that are unobservable and significant to the overall fair value measurement. Due to the inherent uncertainty of determining the fair value of investments that do not have a readily available market value, the fair value of our investments may fluctuate from period to period. Additionally, the fair value of such investments may differ significantly from the values that would have been used had a ready market existed for such investments and may differ materially from the values that may ultimately be realized. Further, such investments are generally less liquid than publicly traded securities and may be subject to contractual and other restrictions on resale. If we were required to liquidate a portfolio investment in a forced or liquidation sale, it could realize amounts that are different from the amounts presented and such differences could be material. In addition, changes in the market environment and other events that may occur over the life of the investments may cause the gains or losses ultimately realized on these investments to be different than the unrealized gains or losses reflected previously.
Equity Securities and Warrants	Equity Securities and Warrants The Company may be issued warrants by portfolio companies as yield enhancements in connection with a related debt investment. These warrants are recorded as assets at estimated fair value on the grant date. The Company determines the cost basis of the warrants or other equity securities received based upon their respective fair values on the date of receipt in proportion to the total fair value of the debt and warrants or other equity securities received. Depending on the facts and circumstances, the Company generally utilizes a combination of one or several forms of the market approach and contingent claim analyses (a form of option analysis) to estimate the fair value of the securities as of the measurement date and determines the cost basis using a relative fair value methodology. As part of its application of the market approach, the Company estimates the enterprise value of a portfolio company utilizing customary pricing multiples, based on the development stage of the underlying issuers, or other appropriate valuation methods, such as considering recent transactions in the equity securities of the portfolio company or third-party valuations that are assessed to be indicative of fair value of the respective portfolio company. If appropriate, based on the facts and circumstances, the Company performs an allocation of the enterprise value to the equity securities utilizing a contingent claim analysis and/or other waterfall calculation by which it allocates the enterprise value across the portfolio company’s warrants and other equity securities in order of their preference relative to one another.
Earnings per share	Earnings per share Basic earnings per share is computed by dividing net increase (decrease) in net assets resulting from operations by the weighted-average number of common shares outstanding for the period. Other potentially dilutive common shares, and the related impact to earnings are considered when calculating earnings per share on a diluted basis using the treasury stock method.
Revenue Recognition	Revenue Recognition Interest Income Interest income is recorded on an accrual basis and includes accretion and amortization of discounts or premiums, respectively. Discounts and premiums to par value on securities purchased are accreted and amortized, respectively, into interest income over the contractual life of the respective security using the effective yield method. The amortized cost of investments includes the original cost adjusted for the accretion and amortization of discounts and premiums, respectively. Upon prepayment of a loan or debt security, any prepayment premiums and unamortized discounts or premiums are recorded as interest income. Certain investments may have contractual payment-in-kind ("PIK") interest or dividends. PIK interest or dividends represents accrued interest or dividends that is added to the principal amount of the investment on the respective interest or dividend payment dates rather than being paid in cash and generally becomes due at maturity. Dividend Income Dividend income on preferred equity securities is recorded on the accrual basis to the extent that such amounts are payable by the portfolio company and are expected to be collected. Dividend income on common equity securities is recorded on the record date for private portfolio companies or on the ex-dividend date for publicly traded portfolio companies. Fee Income All transaction fees earned in connection with our investments are recognized as fee income and are generally non-recurring. Such fees typically include fees for services, including administrative, structuring (including with respect to amendments) and advisory services, provided to portfolio companies. We recognize income from fees for providing such structuring and advisory services when the services are rendered or the transactions are completed, and payment is received (generally immediately). Non-Accrual Policy When a debt security becomes 90 days or more past due, or if management otherwise does not expect that principal, interest, and other obligations due will be collected in full, the Company will generally place the debt security on non-accrual status and cease recognizing interest income on that debt security until all principal and interest due has been paid or the Company believes the borrower has demonstrated the ability to repay its current and future contractual obligations. Any interest receivable is reversed from income in the period that a loan is placed on non-accrual status. However, the Company may make exceptions to this policy if the investment has sufficient collateral value and is in the process of collection. If PIK interest or dividends are not expected to be realized by the Company, the investment generating PIK interest or dividends will be placed on non-accrual status. When an investment with PIK is placed on non-accrual status, the accrued, uncapitalized interest or dividends are generally reversed through interest or dividend income, respectively. As of September 30, 2025 and December 31, 2024, there were no investments placed on non-accrual status.
Unearned Revenue	Unearned Revenue The Company utilizes interest reserves on certain loans which are applied to future interest payments. Such reserves are established at the time of loan origination. The interest reserve is recorded as a liability as it represents unearned interest revenue. The interest reserve is relieved when the interest on the loan is earned, and interest income is recorded in the period when the interest is earned in accordance with the credit agreement. The interest payment is deducted from the interest reserve deposit balance on the date when the interest payment is due. The decision to establish an interest reserve is made during the underwriting process and considers the creditworthiness and expertise of the borrower, and the debt coverage provided by the pledged collateral. It is the Company’s policy to recognize income for this interest component as long as the subject loan is performing as originally projected and if there has been no deterioration in the financial condition of the borrower. The Company’s standard accounting policies for interest income recognition are applied to all loans, including those with interest reserves. As of September 30, 2025 and December 31, 2024, the Company recorded $15,499 and $37,752, respectively, of prepaid interest reserves, which are presented as unearned interest income on the Statements of Assets and Liabilities.
Income Taxes	Income Taxes The Company adopted an initial tax year end of December 31, 2021 and was taxed as a corporation for U.S. federal income tax purposes for the tax period ended December 31, 2021. The Company adopted the tax year end of March 31 and elected to be treated for U.S. federal income tax purposes as a RIC under Subchapter M of the Code for the tax period January 1, 2022 through March 31, 2022 and in subsequent years. The Company intends to maintain such election in the current and future taxable years. To maintain its tax treatment as a RIC, the Company must meet specified source-of-income and asset diversification requirements and timely distribute to its stockholders for each taxable year at least 90% of its investment company taxable income. In order for the Company not to be subject to U.S. federal excise taxes, it must distribute annually an amount at least equal to the sum of (i) 98% of its net ordinary income for the calendar year, (ii) 98.2% of its capital gains in excess of capital losses for the one-year period ending on October 31 of the calendar year and (iii) any net ordinary income and capital gains in excess of capital losses for preceding years that were not distributed during such years. The Company, at its discretion (subject to the requirement to distribute 90% of its investment company taxable income as described above), may carry forward taxable income in excess of calendar year dividends and pay a 4% nondeductible U.S. federal excise tax on this income. If the Company chooses to do so, this generally would increase expenses and reduce the amount available to be distributed to stockholders. For both the three and nine months ended September 30, 2025 and 2024, the Company accrued $2,797 and $31,314, respectively, of excise taxes. As of September 30, 2025 and December 31, 2024, $0 and $88,709, respectively, of accrued excise taxes remained payable. During the quarter ended September 30, 2025, the Company determined that it had overpaid its estimated federal excise tax liability for the prior fiscal year by $23,851. This overpayment resulted in a deferred tax asset and is included in prepaid expenses and other assets on the Statements of Assets and Liabilities. The Company has evaluated the realizability of the deferred tax asset and believes it is more likely than not that the benefit will be realized in future periods through either a refund or application against future excise tax liabilities. Accordingly, no valuation allowance has been recorded against this deferred tax asset. The Company evaluates tax positions taken in the course of preparing the Company’s tax returns to determine whether the tax positions are “more-likely-than-not” to be sustained by the applicable tax authority in accordance with ASC Topic 740, Income Taxes (“ASC 740”). Tax benefits of positions not deemed to meet the more-likely-than-not threshold, or uncertain tax positions, would be recorded as tax expense in the current year. It is the Company’s policy to recognize accrued interest and penalties related to uncertain tax benefits in income tax expense. Based on the analysis of the Company’s tax position, the Company had no uncertain tax positions that met the recognition or measurement criteria as of September 30, 2025 and December 31, 2024. The Company does not anticipate any significant increase or decrease in unrecognized tax benefits for the next twelve months. The Company identifies its major tax jurisdiction as the United States. As of September 30, 2025, the tax years that remain subject to examination by the Internal Revenue Service are from 2022 (commencement of operations) forward.
Distributions	Distributions Distributions to common stockholders are recorded on the record date. The amount of taxable income to be paid out as a distribution is determined by our Board on a quarterly basis and is generally based upon the future taxable income estimated by management. Capital gains, if any, are distributed at least annually, although the Company may decide to retain all or some of those capital gains for investment and pay U.S. federal income tax at corporate rates on those retained amounts. If the Company chooses to do so, this generally will increase expenses and reduce the amount available to be distributed to stockholders. Our distributions may exceed our earnings, and therefore, portions of the distributions that we make may be a return of the money originally invested and represent a return of capital distribution to shareholders for tax purposes.
Offering Costs	Offering Costs These costs consist primarily of legal fees and other costs incurred in connection with issuances of the Company’s common stock, including the preparation of the Company’s registration statement, registration fees, transfer agent expenses, and other expenses relating to the offering. Offering costs are capitalized as deferred offering costs and, if any, are included in prepaid expenses and other assets on the Statements of Assets and Liabilities. As of September 30, 2025 and December 31, 2024, deferred offering costs were $151,284 and $49,998, respectively. The deferred offering costs were charged to capital upon the issuance of shares subsequent to the completion of the Loan Portfolio Acquisition. For the three and nine months ended September 30, 2025, $0 of offering costs were charged to capital. For the year ended December 31, 2024, $1,214,375 of offering costs were charged to capital. As of September 30, 2025 and December 31, 2024, there were $0 and $989,645, respectively, of offering costs that remained payable by the Company.
Transaction Expenses Related to the Loan Portfolio Acquisition	Transaction expenses related to the Loan Portfolio Acquisition Cumulative transaction expenses related to the Loan Portfolio Acquisition through September 30, 2025 and December 31, 2024 were $6,053,043 and $6,053,043, respectively, and consisted primarily of legal fees and valuation fees. For the three and nine months ended September 30, 2025, the Company incurred transaction expenses related to the Loan Portfolio Acquisition of $0. For the three and nine months ended September 30, 2024, the Company incurred transaction expenses related to the Loan Portfolio Acquisition of $2,429,993 and $5,069,062, respectively. As of September 30, 2025 and December 31, 2024, $0 and $2,945,125, respectively, of transaction expenses related to the Loan Portfolio Acquisition remained payable, and are included in transaction fees payable on the Statements of Assets and Liabilities.
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs consist of origination expenses incurred in connection with the closing, or anticipated closing, of a credit facility, and include legal, accounting, and other related expenses. These costs are deferred and amortized as interest expense using the straight-line method over the term of the applicable credit facility. In addition to origination expenses, the Company pays an annual upfront fee related to its credit facility. These fees are deferred and amortized as interest expense using the straight-line method over a one-year term. Deferred financing costs are included in prepaid expenses and other assets on the Statements of Assets and Liabilities. As of September 30, 2025 and December 31, 2024, deferred financing costs payable were $0 and $47,881, respectively.
New Accounting Standards	New Accounting Standards On January 1, 2025, the Company adopted Accounting Standards Update ("ASU") No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures, which requires, among other things, greater disaggregation of information in the income tax rate reconciliation and for paid income taxes to be disaggregated by jurisdiction. This ASU affects financial statement disclosure only, which is not required until year end 2025 and, as a result, does not affect our results of operations or financial condition. In November 2024, the FASB issued ASU No. 2024-03, Income Statement - Reporting Comprehensive Income - Expense Disaggregation Disclosures (Subtopic 220-40). ASU No. 2024-03 requires disaggregated disclosure of certain costs and expenses, including purchase of inventory, employee compensation, depreciation, amortization and depletion, within relevant income statement captions. ASU 2024-03 is effective for annual years beginning after December 15, 2026, and interim periods beginning after December 15, 2027. Early adoption and retrospective application are permitted. The Company is currently evaluating the impact of adopting ASU No. 2024-03.

Chicago Atlantic BDC, Inc. 10-Q