MASTEC INC

Shareholders and Board of Directors

Coral Gables, Florida

Opinion on the Consolidated Financial Statements

We have audited the accompanying consolidated balance sheets of MasTec, Inc. (the “Company”) as of December 31, 2023 and 2022, the related consolidated statements of operations and comprehensive income, equity, and cash flows for each of the three years in the period ended December 31, 2023, and the related notes and financial statement schedule (collectively referred to as the “consolidated financial statements”). In our opinion, based on our audits and the report of the other auditors, the consolidated financial statements present fairly, in all material respects, the financial position of the Company at December 31, 2023 and 2022, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2023, in conformity with accounting principles generally accepted in the United States of America.

We also have audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States) (“PCAOB”), the Company's internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control – Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (“COSO”) and our report dated February 29, 2024 expressed an unqualified opinion thereon.

We did not audit the financial statements of IEA Energy Services, LLC and subsidiaries (“IEA LLC”), a wholly-owned subsidiary of the Company, which statements reflect total assets of $686.6 million at December 31, 2023, and total revenues of $1,732.1 million for the year then ended. Those statements were audited by other auditors whose report has been furnished to us, and our opinion, insofar as it relates to the amounts included for IEA LLC, is based solely on the report of the other auditors.

Basis for Opinion

These consolidated financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’s consolidated financial statements based on our audits. We are a public accounting firm registered with the PCAOB and are required to be independent with respect to the Company 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 consolidated financial statements are free of material misstatement, whether due to error or fraud.

Our audits included performing procedures to assess the risks of material misstatement of the consolidated 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 consolidated 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 consolidated financial statements. We believe that our audits and the report of the other auditors provide a reasonable basis for our opinion.

Critical Audit Matters

The critical audit matters communicated below are matters arising from the current period audit of the consolidated financial statements that were communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matters below, providing separate opinions on the critical audit matters or on the accounts or disclosures to which they relate.

Goodwill Impairment Assessment

As described in Notes 1 and 3 to the consolidated financial statements, the Company’s consolidated goodwill balance was $2.1 billion at December 31, 2023. The Company performs annual impairment tests of goodwill, and on a quarterly basis, monitors goodwill for potential indicators of impairment. During 2023, the Company concluded that triggering events occurred for certain reporting units. No impairment charges were recorded as a result of the Company’s interim and annual impairment tests. Management estimates the fair values of its reporting units using a combination of the market and the income approaches.

We identified the determination of the fair value of certain reporting units as a critical audit matter. Under the market approach, the reporting units’ fair values were estimated using market multiple assumptions for comparable companies. Under the income approach, a discounted cash flow methodology was used that included: (i) management’s estimates and assumptions, such as discount rates, terminal growth rates, and projections of revenue, operating costs, and cash flows, (ii) assumptions related to general economic and market conditions, and (iii) considerations of planned business and operational strategies. These estimates and assumptions require significant management judgment due to their highly subjective nature. Changes in these assumptions could have a significant impact on the fair value of the reporting units and the amount of goodwill impairment (if any). These estimates and assumptions were especially challenging to test and required significant auditor judgment because they were affected by expected future market conditions. In addition, the audit effort involved the use of professionals with specialized skill and knowledge.

The primary procedures we performed to address this critical audit matter included:

•Testing the design and operating effectiveness of controls related to management’s goodwill impairment assessment, including controls over management’s review of (i) the budgeting and forecasting, and (ii) the data and significant estimates and assumptions used to determine the fair value of the reporting units.

•Evaluating the appropriateness of the methodologies and the reasonableness of the assumptions used by management in determining the fair value of the reporting units, including:

•With respect to the market approach, assessing the appropriateness of the approach and evaluating the reasonableness of the comparable companies and market multiples selected for the reporting units.

•With respect to the income approach, assessing the appropriateness of the discounted cash flow methodology and evaluating the reasonableness of assumptions used by: (i) evaluating the reasonableness of projected revenues and operating costs against recent performance and revenue backlogs, (ii) assessing the reasonableness of management’s expected success rates for winning new project awards against recent reporting units’ performance, (iii) evaluating the general economic and market conditions, including expectations for market growth against industry reports and reporting unit specific events including recent and projected financial performance, (iv) testing the completeness, accuracy, and relevance of underlying data used in the models, and (v) performing sensitivity analyses of individual reporting units’ cash flow projections.

•Testing management’s reconciliation of the estimated fair value of the Company’s reporting units to the indicated market capitalization of the Company as a whole.

•Utilizing internal valuation specialists to assist in (i) assessing the appropriateness and relative weighting of the income and market approaches, and (ii) evaluating the reasonableness of the discount rates and terminal growth rates used in the income approach.

Revenue Recognition - Estimated Costs to Complete

As described in Note 1 to the consolidated financial statements, the Company recognizes a significant portion of its revenue over time using the cost-to-cost measure of progress, which measures a contract’s progress toward completion based on the ratio of actual contract costs incurred to date to the Company’s estimated costs at completion. The cost estimation process for these contracts is based on the knowledge and experience of the Company’s project managers, engineers, and financial professionals. Changes in job performance, job conditions and management’s assessment of expected variable consideration are factors that influence estimates of the total contract transaction price, total costs to complete those contracts and the Company’s revenue recognition.

We identified estimated costs to complete on certain revenue contracts as a critical audit matter. The determination of the total estimated cost and progress toward completion requires management to make significant estimates and assumptions. Total estimated costs to complete projects include various costs such as direct labor, material, and subcontract costs. Changes in these estimates can have a significant impact on the revenue recognized each period. Auditing these estimates involved especially challenging auditor judgment in evaluating the reasonableness of management’s assumptions and estimates over the duration of these contracts.

The primary procedures we performed to address this critical audit matter included:

•Testing the design and operating effectiveness of certain controls related to estimated costs to complete, including controls over management’s review of: (i) the development of project budgets and the key cost inputs, (ii) the ongoing assessment and revisions to project budgets, and (iii) the ongoing review of project status, including the nature of activities to complete open projects.

•Evaluating the reasonableness of management’s budgeting process by selecting a sample of project budgets for projects that were completed during the period and performing a retrospective review of budget to actual variances.

•Assessing the reasonableness of the estimated costs to complete by selecting a sample of open projects and: (i) evaluating the reasonableness of project budgets and the nature of costs required to complete the project, (ii) assessing the status of completion by testing of a sample of project costs incurred to date, (iii) evaluating the reasonableness of project status by observing project review meetings and performing inquiries of project managers to assess the nature of activities required to complete the project, and (iv) performing a retrospective review of the project and investigating budget to actual variances (if any).

•Assessing the reasonableness of changes in estimated costs to complete by comparing project profitability estimates in the current period to historical estimates and actual performance and investigating reasons for changes in expected costs and project margins.

/s/ BDO USA, P.C.

We have served as the Company’s auditor since 2004.

Miami, Florida

To the shareholders and the Board of Directors of MasTec, Inc.

Opinions on the Financial Statements and Internal Control over Financial Reporting

We have audited the consolidated balance sheet of IEA Energy Services, LLC and its consolidated subsidiaries (“IEA LLC”) as of December 31, 2023, the related consolidated statements of operations, members’ equity (deficit), and cash flows, for the year ended December 31, 2023, and the related notes (collectively referred to as the "financial statements" and not presented herein). We also have audited IEA LLC’s internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control — Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the financial statements referred to above present fairly, in all material respects, the financial position of IEA LLC as of December 31, 2023, and the results of its operations and its cash flows for the year ended December 31, 2023, in conformity with accounting principles generally accepted in the United States of America. Also, in our opinion, IEA LLC maintained, in all material respects, effective internal control over financial reporting as of December 31, 2023, based on criteria established in Internal Control — Integrated Framework (2013) issued by COSO.

Basis for Opinions

IEA LLC’s management is responsible for these financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Annual Report on Internal Control Over Financial Reporting (not presented herein). Our responsibility is to express an opinion on these financial statements and an opinion on IEA LLC’s internal control over financial reporting 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 IEA LLC 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 and in accordance with auditing standards generally accepted in the United States of America. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audit of the financial statements included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures to respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audit also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

Definition and Limitations of Internal Control over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of IEA LLC; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of IEA LLC are being made only in accordance with authorizations of management and directors of IEA LLC; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of IEA LLC’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Other Matter

As discussed in Note 10 to the IEA LLC financial statements, IEA LLC engages in significant transactions with affiliates such as MasTec, Inc. and Infrastructure and Energy Alternatives, Inc. Portions of certain income and expenses represent allocations made from affiliates for items applicable to IEA LLC as a whole. Therefore, the financial statements of IEA LLC have been prepared from the separate records maintained by IEA LLC and its parent and may not be indicative of the conditions that would have existed or the results of operations if IEA LLC had been operated as an unaffiliated company.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current-period audit of the financial statements that was communicated or required to be communicated to the audit committee and that (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Revenue Recognition for Unapproved Change Orders – Refer to Note 1 to the Financial Statements

Critical Audit Matter Description

Revenue from construction contracts is recognized over time using the cost-to-cost measure of progress. Management reviews estimates of total contract transaction price and total project costs on an ongoing basis. Changes in job performance, job conditions, and management’s assessment of expected variable considerations are factors that influence estimates of the total contract transaction price, total costs to complete those contracts, and profit recognition.

Transaction pricing for IEA LLC’s contracts may include variable consideration, including items such as change orders. Management estimates variable consideration for a performance obligation utilizing estimation methods that best predict the amount of consideration to which IEA LLC will be entitled. Variable consideration is included in the estimated transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is resolved. Management’s estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based on past practices with the customer, specific discussions, correspondence or preliminary negotiations with the customer, legal evaluations, and all other relevant information that is reasonably available.

To the extent unapproved change orders are not resolved in IEA LLC’s favor, there could be reductions in, or reversals of, previously recognized revenue. As of December 31, 2023, IEA LLC included $30.4 million of unapproved change orders in the transaction price for certain contracts that were in the process of being resolved in the normal course of business, including through negotiation, arbitration, and other proceedings.

We identified revenue recognition related to unapproved change orders as a critical audit matter because of the judgments necessary for management to determine the variable consideration related to unapproved change orders and the extent of audit effort and degree of auditor judgment when performing procedures to audit management’s estimates of revenue related to unapproved change orders.

How the Critical Audit Matter Was Addressed in the Audit

Our audit procedures related to management’s estimates of variable consideration related to unapproved change orders used in the transaction price to recognize revenue on construction contracts included the following, among others:

•We tested the design and effectiveness of controls over IEA LLC’s unapproved change orders and estimates of variable consideration.

•We tested the mathematical accuracy of management’s calculation of revenue recognized from unapproved change orders.

•We compared historical estimates of variable consideration to actual results to evaluate management’s estimates.

•For a selection of contracts identified with significant unapproved change orders, we performed the following:

– Evaluated IEA LLC’s variable consideration against the contract provisions.

– Evaluated details of the underlying costs included in the unapproved change orders.

– Obtained available correspondence with customers.

– Performed inquiries with project managers and executive management, including those independent of accounting.

– Obtained a legal evaluation of the contractual provisions from internal counsel.

– Performed inquiries with project management and executive management, including those independent of accounting.

– Obtained a legal evaluation of the contractual provisions from internal counsel.

/s/Deloitte & Touche LLP

Indianapolis, Indiana

We have served as IEA LLC’s auditor since 2018.