Business and Organization	6 Months Ended
Jun. 30, 2026
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Organization	Note 1: Business and Organization Organization Custom Truck One Source, Inc., a Delaware corporation, and its wholly owned subsidiaries (“we,” “our,” “us,” or “the Company”) are engaged in the business of providing a range of products and services to customers through rentals and sales of specialty equipment, rentals and sales of aftermarket parts and services related to the specialty equipment, and repair, maintenance and customization services related to that equipment. We are a specialty equipment provider to the electric utility transmission and distribution, telecommunications, rail, forestry, waste management and other infrastructure-related industries in North America. Our core business relates to our new equipment inventory and rental fleet of specialty equipment that is utilized by service providers in infrastructure development and improvement work. We offer our specialized equipment to a diverse customer base, including utilities and contractors, for the maintenance, repair, upgrade, and installation of critical infrastructure assets, including distribution and transmission electric lines, telecommunications networks and rail systems, as well as for lighting and signage. We rent, produce, sell and service a broad range of new and used equipment, including bucket trucks, digger derricks, dump trucks, cranes, service trucks, and heavy-haul trailers. After a recent evaluation of how we currently assess overall operational decision-making and report internal financial information, beginning January 1, 2026, we are reporting the financial results of our two operating segments, which will also be our two reportable segments: (1) Specialty Equipment Rentals (“SER”), which comprises our legacy Equipment Rental Solutions (“ERS”) segment (except for certain used sales to be accounted for by STEM, defined below), plus a portion of our legacy Aftermarket Parts and Services (“APS”) segment, and (2) Specialty Truck Equipment & Manufacturing (“STEM”), which comprises our legacy Truck and Equipment Sales (“TES”) segment, certain used sales that previously were accounted for by ERS, plus a portion of our legacy APS segment. Additionally, beginning January 1, 2026, our segment reporting reflects intersegment sales and a gross margin. This new structure better represents the financial profile and economics of our rental and sales & manufacturing businesses. Refer to Note 14: Segments, for additional segment information and a recast of prior period segment financial information. Basis of Presentation Our accompanying condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”). Our condensed consolidated financial statements include the accounts of all wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The preparation of financial statements in accordance with GAAP requires that these Unaudited Condensed Consolidated Financial Statements and most of the disclosures in these Notes be presented on a historical basis, as of or for the current interim period ended or comparable prior period. The accompanying interim statements of the Company have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X, and the Condensed Consolidated Balance Sheet at December 31, 2025 has been derived from the audited consolidated financial statements of Custom Truck One Source, Inc. at that date. Accordingly, these interim financial statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring adjustments and disclosures necessary for a fair statement of these interim statements, have been included. The results reported in these interim statements are not necessarily indicative of the results that may be reported for the entire year or for any other periods. These interim statements should be read in conjunction with the Custom Truck One Source, Inc. audited consolidated financial statements included in the Custom Truck One Source, Inc. Annual Report on Form 10-K for the year ended December 31, 2025. Use of 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 contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates. Recently Issued Accounting Standards In December 2025, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2025-11 — Interim Reporting (Topic 270): Narrow-Scope Improvements (“ASU 2025-11”), which is intended to improve the navigability of the guidance in ASC 270, Interim Reporting, and clarify when it applies. Under the amendments, an entity is subject to ASC 270 if it provides interim financial statements and notes in accordance with GAAP. ASU 2025-11 also addresses the form and content of such financial statements, interim disclosures requirements, and establishes a principle under which an entity must disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027, and early adoption is permitted. The Company is currently assessing the impact ASU 2025-11 may have on its condensed consolidated financial statements and disclosures. In September 2025, the FASB issued ASU No. 2025-06, Intangibles — Goodwill and Other — Internal-Use Software (“ASU 2025-06”), which amends the guidance for accounting for software costs to reflect current software development practices, including iterative and agile methodologies, by removing references to development stages. It also clarifies the criteria for capitalization, which begins when both of the following occur: (1) management has authorized and committed to funding the software project and (2) it is probable that the project will be completed and the software will be used to perform the function intended. ASU 2025-06 is effective for fiscal years beginning after December 15, 2027, and interim periods within those fiscal years. Early adoption is permitted. The amendments may be applied either prospectively, retrospectively, or utilizing a modified transition approach. The Company is currently assessing the impact of ASU 2025-06 on its condensed consolidated financial statements and disclosures. In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (“ASU 2024-03”), which requires additional disclosures in the notes to financial statements, disaggregating specific expense categories within relevant income statement captions. The FASB further clarified the effective date in January 2025 with the issuance of ASU 2025-01, Income Statement — Reporting Comprehensive Income — Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date (“ASU 2025-01”). ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The Company is currently assessing the impact of the requirements on its condensed consolidated financial statements and disclosures.

Custom Truck One Source, Inc., a Delaware corporation, and its wholly owned subsidiaries (“we,” “our,” “us,” or “the Company”) are engaged in the business of providing a range of products and services to customers through rentals and sales of specialty equipment, rentals and sales of aftermarket parts and services related to the specialty equipment, and repair, maintenance and customization services related to that equipment.

We are a specialty equipment provider to the electric utility transmission and distribution, telecommunications, rail, forestry, waste management and other infrastructure-related industries in North America. Our core business relates to our new equipment inventory and rental fleet of specialty equipment that is utilized by service providers in infrastructure development and improvement work. We offer our specialized equipment to a diverse customer base, including utilities and contractors, for the maintenance, repair, upgrade, and installation of critical infrastructure assets, including distribution and transmission electric lines, telecommunications networks and rail systems, as well as for lighting and signage. We rent, produce, sell and service a broad range of new and used equipment, including bucket trucks, digger derricks, dump trucks, cranes, service trucks, and heavy-haul trailers.

After a recent evaluation of how we currently assess overall operational decision-making and report internal financial information, beginning January 1, 2026, we are reporting the financial results of our two operating segments, which will also be our two reportable segments: (1) Specialty Equipment Rentals (“SER”), which comprises our legacy Equipment Rental Solutions (“ERS”) segment (except for certain used sales to be accounted for by STEM, defined below), plus a portion of our legacy Aftermarket Parts and Services (“APS”) segment, and (2) Specialty Truck Equipment & Manufacturing (“STEM”), which comprises our legacy Truck and Equipment Sales (“TES”) segment, certain used sales that previously were accounted for by ERS, plus a portion of our legacy APS segment. Additionally, beginning January 1, 2026, our segment reporting reflects intersegment sales and a gross margin. This new structure better represents the financial profile and economics of our rental and sales & manufacturing businesses. Refer to Note 14: Segments, for additional segment information and a recast of prior period segment financial information.

Our accompanying condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles (“GAAP”). Our condensed consolidated financial statements include the accounts of all wholly-owned subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. The preparation of financial statements in accordance with GAAP requires that these Unaudited Condensed Consolidated Financial Statements and most of the disclosures in these Notes be presented on a historical basis, as of or for the current interim period ended or comparable prior period.

The accompanying interim statements of the Company have been prepared in accordance with GAAP for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X, and the Condensed Consolidated Balance Sheet at December 31, 2025 has been derived from the audited consolidated financial statements of Custom Truck One Source, Inc. at that date. Accordingly, these interim financial statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring adjustments and disclosures necessary for a fair statement of these interim statements, have been included. The results reported in these interim statements are not necessarily indicative of the results that may be reported for the entire year or for any other periods. These interim statements should be read in conjunction with the Custom Truck One Source, Inc. audited consolidated financial statements included in the Custom Truck One Source, Inc. Annual Report on Form 10-K for the year ended December 31, 2025.

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 contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.

In December 2025, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standards Update (“ASU”) No. 2025-11 — Interim Reporting (Topic 270): Narrow-Scope Improvements (“ASU 2025-11”), which is intended to improve the navigability of the guidance in ASC 270, Interim Reporting, and clarify when it applies. Under the amendments, an entity is subject to ASC 270 if it provides interim financial statements and notes in accordance with GAAP. ASU 2025-11 also addresses the form and

content of such financial statements, interim disclosures requirements, and establishes a principle under which an entity must disclose events since the end of the last annual reporting period that have a material impact on the entity. ASU 2025-11 is effective for interim reporting periods within annual reporting periods beginning after December 15, 2027, and early adoption is permitted. The Company is currently assessing the impact ASU 2025-11 may have on its condensed consolidated financial statements and disclosures.

In September 2025, the FASB issued ASU No. 2025-06, Intangibles — Goodwill and Other — Internal-Use Software (“ASU 2025-06”), which amends the guidance for accounting for software costs to reflect current software development practices, including iterative and agile methodologies, by removing references to development stages. It also clarifies the criteria for capitalization, which begins when both of the following occur: (1) management has authorized and committed to funding the software project and (2) it is probable that the project will be completed and the software will be used to perform the function intended. ASU 2025-06 is effective for fiscal years beginning after December 15, 2027, and interim periods within those fiscal years. Early adoption is permitted. The amendments may be applied either prospectively, retrospectively, or utilizing a modified transition approach. The Company is currently assessing the impact of ASU 2025-06 on its condensed consolidated financial statements and disclosures.

In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses (“ASU 2024-03”), which requires additional disclosures in the notes to financial statements, disaggregating specific expense categories within relevant income statement captions. The FASB further clarified the effective date in January 2025 with the issuance of ASU 2025-01, Income Statement — Reporting Comprehensive Income — Expense Disaggregation Disclosures (Subtopic 220-40): Clarifying the Effective Date (“ASU 2025-01”). ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and interim periods within fiscal years beginning after December 15, 2027. Early adoption is permitted. The Company is currently assessing the impact of the requirements on its condensed consolidated financial statements and disclosures.