The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America (“GAAP”) requires the use of estimates and assumptions by management in determining the reported amounts of assets and liabilities, disclosures of contingent liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Estimates are primarily used in our revenue recognition of construction in progress, fair value assumptions in accounting for business combinations and analyzing goodwill, investments, intangible assets and long-lived asset impairments and adjustments, allowance for doubtful accounts receivable, stock-based compensation, reserves for legal matters, realizability of deferred tax assets, unrecognized tax benefits and self-insured claims liabilities and related reserves.

Inventories consist of raw materials, work in process, finished goods, and parts and supplies held for use in the ordinary course of business. Inventory is valued at the lower of cost or net realizable value generally using the historical average cost or first-in, first-out (FIFO) method. When circumstances dictate, we write down inventory to its estimated net realizable value based on assumptions about future demand, market conditions, plans for disposal, and physical condition of the product. Where shipping and handling costs on inventory purchases are borne by us, these charges are included in inventory and charged to cost of services upon use in our projects or the providing of services.

Our investments in entities where we do not have the ability to exercise significant influence are accounted for using the cost method of accounting. Each period, we evaluate whether an event or change in circumstances has occurred that may indicate an investment has been impaired. If, upon further investigation of such events, we determine the investment has suffered a decline in value that is other than temporary, we write down the investment to its estimated fair value.

Expenditures for repairs and maintenance are charged to expense when incurred. Expenditures for major renewals and betterments, which extend the useful lives of existing property and equipment, are capitalized and depreciated. Upon retirement or disposition of property and equipment, the capitalized cost and related accumulated depreciation are removed from the accounts and any resulting gain or loss is recognized in the statements of comprehensive income in the caption (gain) loss on sale of assets.

Goodwill attributable to each reporting unit is tested for impairment either by comparing the fair value of each reporting unit with its carrying value or by a qualitative assessment. These impairment tests are required to be performed at least annually. On an ongoing basis (absent any impairment indicators), we perform an impairment test annually using a measurement date of September 30. In evaluating goodwill for impairment, we have the option to first assess qualitative factors to determine whether it is more likely than not that the fair value of a reporting unit is greater than its carrying value. If we determine that it is more likely than not that the carrying value of a reporting unit is greater than its fair value, then we perform an impairment test by calculating the fair value of the reporting unit and comparing this calculated fair value with the carrying value of the reporting unit.

We estimate the fair value of the reporting unit based on both a market approach and an income approach, using discounted estimated future cash flows. The market approach uses market multiples of enterprise value to earnings before interest, taxes, depreciation and amortization for comparable publicly traded companies. The income approach relies on significant estimates for future cash flows, projected long-term growth rates, and the weighted average cost of capital.

Debt issuance costs are included as a reduction of our debt outstanding, or alternately classified within other non-current assets if we have no borrowings drawn on our credit facility at the balance sheet date, and are amortized to interest expense over the scheduled maturity of the debt. Amortization expense of debt issuance costs was $318, $288 and $294, respectively, for the years ended 2019, 2018 and 2017. Remaining unamortized capitalized debt issuance costs were $782 and $912 at September 30, 2019, and 2018, respectively.

Revenue is generally recognized from a contract with a customer when: (i) it has approval and commitment from both parties, (ii) the rights of the parties are identified, (iii) payment terms are identified, (iv) the contract has commercial substance, and (v) collectability of consideration is probable. We consider the start of a project to be when the above criteria have been met and we have written authorization from the customer to proceed.

some other measure of progress. We recognize revenue on both signed contracts and change orders. A discussion of our treatment of claims and unapproved change orders is described later in this section. Percentage of completion for construction contracts is measured principally by the percentage of costs incurred and accrued to date for each contract to the estimated total cost for each contract at completion. We generally consider contracts to be substantially complete upon departure from the work site and acceptance by the customer. Contract costs include all direct material, labor and insurance costs and those indirect costs related to contract performance, such as indirect labor, supplies, tools, repairs and depreciation costs. Changes in job performance, job conditions, estimated contract costs and profitability and final contract settlements can result in change orders under which the customer agrees to pay additional contract price. Revisions can also result in claims we might make against the customer to recover additional costs that have not been resolved through change orders with the customer. Except in certain circumstances, we do not recognize revenue or margin based on change orders or claims until they have been agreed upon with the customer. The amount of revenue associated with unapproved change orders and claims was immaterial for the years ended September 30, 2019, 2018 and 2017. Provisions for total estimated losses on uncompleted contracts are made in the period in which such losses are determined. The balances billed but not paid by customers pursuant to retainage provisions in project contracts are typically due upon completion of the contracts and acceptance by the customer. Based on our experience, the retention balance at each balance sheet date will be collected within the subsequent fiscal year.

We record accounts receivable for all amounts billed and not collected. Generally, we do not charge interest on outstanding accounts receivable; however, from time to time we may believe it necessary to charge interest on a case by case basis. Additionally, we provide an allowance for doubtful accounts for specific accounts receivable where collection is considered doubtful as well as for general unknown collection issues based on historical trends. Accounts receivable not determined to be collectible are written off as deemed necessary in the period such determination is made. As is common in our industry, some of these receivables are in litigation or require us to exercise our contractual lien rights in order to collect. Our allowance for doubtful accounts at September 30, 2019 and 2018 was $1,184 and $868, respectively. We believe that our allowance for doubtful accounts is sufficient to cover uncollectible receivables as of September 30, 2019.

We regularly evaluate valuation allowances established for deferred tax assets for which future realization is uncertain. We perform this evaluation on a quarterly basis. The estimation of required valuation allowances includes estimates of future taxable income. In assessing the realizability of deferred tax assets at September 30, 2019, we concluded, based upon the assessment of positive and negative evidence, that it is more likely than not that the Company will generate sufficient taxable income within the applicable NOL carryforward periods to realize its net deferred tax assets of $40,874. We considered the scheduled reversal of deferred tax liabilities, projected future taxable income and tax planning strategies in making this assessment. If actual future taxable income is different from these estimates, our results could be affected.

We retain the risk for workers’ compensation, employer’s liability, automobile liability, construction defects, general liability and employee group health claims, as well as pollution coverage, resulting from uninsured deductibles per accident or occurrence which are generally subject to annual aggregate limits. Our general liability program provides coverage for bodily injury and property damage. In many cases, we insure third parties, including general contractors, as additional insureds under our insurance policies. Losses are accrued based upon our known claims incurred and an estimate of claims incurred but not reported. Each year, we compile our historical data pertaining to the insurance experiences and actuarially develop the ultimate loss associated with our insurance programs other than pollution coverage for our Infrastructure Solutions segment. We believe that the actuarial valuation provides the best estimate of the ultimate losses to be expected under these programs.

We elect to discount the ultimate losses above to present value using an approximate risk-free rate over the average life of our insurance claims. For the years ended September 30, 2019 and 2018, the discount rate used was 1.6 percent and 2.9 percent, respectively. The present value of all insurance reserves for the employee group health claims, workers’ compensation, auto and general liability recorded at September 30, 2019, and 2018 was $6,683 and $6,202, respectively. Our employee group health claims are anticipated to be resolved within the year ended September 30, 2020.

We evaluate the recoverability of property and equipment and other long-lived assets as facts and circumstances indicate that any of those assets might be impaired. If an evaluation is required for our assets we plan to hold and use, the estimated future undiscounted cash flows associated with the asset are compared to the asset’s carrying amount to determine if an impairment of such property has occurred. The effect of any impairment would be to expense the difference between the fair value of such property and its carrying value. Estimated fair values are determined based on expected future cash flows discounted at a rate we believe incorporates the time value of money, the expectations about future cash flows and an appropriate risk premium.

Financial instruments, which potentially subject us to concentrations of credit risk, consist principally of cash deposits and accounts receivable. Through delayed payment terms, we at times grant credit, usually without collateral, to our customers, who are generally large public companies, contractors and homebuilders throughout the United States. Consequently, we are subject to potential credit risk related to changes in business and economic factors throughout the United States, specifically, within the construction, homebuilding and mission critical facility markets. However, we are entitled to payment for work performed and generally have certain lien rights in that work. Further, management believes that its contract acceptance, billing and collection policies are adequate to manage potential credit risk. We routinely maintain cash balances in financial institutions in excess of federally insured limits. We periodically assess the financial condition of these institutions where these funds are held and believe the credit risk is minimal. We maintain the majority of our cash and cash equivalents in money market mutual funds. There can be no assurance, however, that we will not be adversely affected by credit risks we face.

We measure and record compensation expense for all share-based payment awards based on the fair value of the awards granted at the date of grant. The fair value of restricted stock awards and phantom stock unit awards is determined based on the number of shares granted and the closing price of IES’s common stock on the date of grant. For awards vesting upon achievement of a market condition, the likelihood of achieving that market condition is considered in determining the fair value of the grant, which we expense ratably over the

The Company maintains a rabbi trust to fund certain deferred compensation plans. The securities held by the trust are classified as trading securities. The investments are recorded at fair value and are classified as other non-current assets in the accompanying Consolidated Balance Sheets as of September 30, 2019, and 2018. The changes in fair values are recorded as a component of other income (expense) in the Consolidated Statements of Comprehensive Income (Loss).

In connection with our acquisitions of STR Mechanical, LLC (“STR Mechanical”) in fiscal 2016 and NEXT Electric, LLC (“NEXT Electric”) in fiscal 2017, we acquired 80 percent interests in these entities, and the remaining 20 percent was retained by the third party sellers. The interests retained by those third party sellers are identified on our Consolidated Balance Sheets as noncontrolling interest, classified outside of permanent equity. Under the terms of the operating agreements governing these entities, after five years from the dates of the acquisitions, we may elect to purchase, or the third party sellers may require us to purchase, part of all of the remaining 20 percent interests in these entities. The purchase price is variable, based on a multiple of earnings as defined in the operating agreements. Therefore, this noncontrolling interest is carried at the greater of the balance determined under ASC 810 and the redemption amounts assuming the noncontrolling interests were redeemable at the balance sheet date. If all of these interests had been redeemable at September 30, 2019, the redemption amount would have been $3,294. For the year ended September 30, 2018, we recorded an increase to retained earnings of $44 to offset an increase to noncontrolling interest recorded in fiscal 2017, decreasing the carrying amount of the noncontrolling interest in STR to the balance determined under ASC 810, as if it had been redeemable at September 30, 2018, as the redemption amount would have been less than the carrying amount.

In February 2016, the Financial Accounting Standards Board (the “FASB”) issued Accounting Standard Update No. 2016-02, Leases (“ASU 2016-02”). Under ASU 2016-02, we will recognize a right-of-use asset and a lease liability on our Balance Sheet for all leases, other than those that meet the definition of a short-term lease. For income statement purposes, leases must be classified as either operating or finance. Operating leases will result in straight-line expense, similar to current operating leases, while finance leases will be accounted for similar to current capital leases. We plan to adopt this standard on October 1, 2019, using a modified retrospective transition approach. We plan to utilize the optional transition method allowed under Accounting Standard Update No. 2018-11, which allows the recognition of a cumulative-effect adjustment to retained earnings on such date and the continued reporting of retrospective periods using the previous accounting standards. We plan to elect all of the available practical expedients, which would allow the use of hindsight in the determination of the lease term and impairment assessment of the right-of-use assets, and eliminate the need to reassess whether our existing or expired contracts contain a lease and its corresponding classification. We have developed processes and internal controls to meet the reporting and disclosure requirements of the standard, including the validation and detailed assessment of our full lease population. Our balance sheet will be impacted from this standard by recording lease right-of-use assets and lease liabilities in similar amounts, which we currently estimate to be less than $35 million as of October 1, 2019, with any difference between the right-of-use asset and the lease liabilities recorded to previously accrued or deferred rent expense relating to prior periods. We do not anticipate that the standard will have a significant impact on our net earnings, cash flows or compliance with the financial covenants under our revolving credit facility.

In June 2016, the FASB issued Accounting Standard Update No. 2016-13, Financial Instruments – Credit Losses (“ASU 2016-13”), which requires companies to consider historical experiences, current market conditions and reasonable and supportable forecasts in the measurement of expected credit losses, with further clarifications made in April 2019 and May 2019 with the issuances of Accounting Standard Updates No. 2019-04 and 2019-05. This update is effective for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years, although early adoption is permitted. We are currently evaluating the impact it will have on our Consolidated Financial Statements. We plan to adopt this standard on October 1, 2020.

In June 2018, the FASB issued Accounting Standard Update No. 2018-07, Compensation—Stock Compensation (“ASU 2018-07”), to simplify the accounting for share-based payments to nonemployees by aligning it with the accounting for share-based payments for employees, with certain exceptions. Under the new guidance, the cost for nonemployee awards may be lower and less volatile than under current GAAP because the measurement generally will occur earlier and will be fixed at the grant date. This update is effective for the fiscal year ended September 30, 2020.

In August 2018, the FASB issued Accounting Standard Update No. 2018-13, Fair Value Measurement Disclosure Framework (“ASU 2018-13”), to modify certain disclosure requirements for fair value measurements. Under the new guidance, registrants will need to disclose weighted average information for significant unobservable inputs for all Level 3 fair value measurements. The guidance does not specify how entities should calculate the weighted average, but requires them to explain their calculation. The new guidance also requires disclosing the changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements of instruments held at the end of the reporting period. This guidance is effective for fiscal years beginning after December 15, 2019 and for interim periods within those fiscal years, although early adoption is permitted for either the entire standard or only the provisions that eliminate or modify the requirements.

In May 2014, the FASB issued Accounting Standard Update No. 2014-09, which provides a single comprehensive accounting standard for revenue recognition for contracts with customers and supersedes prior industry-specific guidance. The new standard requires companies to recognize revenue when control of promised goods or services is transferred to customers at an amount that reflects the consideration to which the company expects to be entitled. The new model requires companies to identify contractual performance obligations and determine whether revenue should be recognized at a point in time or over time for each obligation. The new standard also expands disclosure requirements regarding revenue and cash flows arising from contracts with customers.

We adopted the new revenue recognition standard on October 1, 2018 (“Adoption Date”), using the modified retrospective method, which provides for a cumulative effect adjustment to beginning fiscal 2019 retained earnings for uncompleted contracts impacted by the adoption. We recorded an adjustment of $80 to beginning fiscal 2019 retained earnings as a result of adoption of the new standard. The changes to the method and/or timing of our revenue recognition associated with the new standard primarily affect revenue recognition within our Infrastructure Solutions segment for which, as of October 1, 2018, certain of our contracts do not qualify for revenue recognition over time. In addition, we have now combined in process contracts that historically had been accounted for as separate contracts in cases where those contracts meet the criteria for combination of contracts under the new standard, and we now capitalize certain commissions which were previously expensed when incurred. The impact on our results for the year ended September 30, 2019, of applying the new standard to our contracts was not material.

Consistent with our adoption method, the comparative prior period information continues to be reported using the previous accounting standards in effect for the period presented. We have elected to utilize the modified retrospective transition practical expedient that allows us to evaluate the impact of contract modifications as of the Adoption Date rather than evaluating the impact of the modifications at the time they occurred prior to the Adoption Date.

In January 2016, the FASB issued Accounting Standard Update No. 2016‑01, Financial Instruments. This standard is associated with the recognition and measurement of financial assets and liabilities, with further clarifications made in February 2018 with the issuance of Accounting Standard Update No. 2018-03. The amended guidance requires certain equity investments that are not consolidated and not accounted for under the equity method to be measured at fair value with changes in fair value recognized in net income rather than as a component of accumulated other comprehensive income (loss). It further states that an entity may choose to measure equity investments that do not have readily determinable fair values using a quantitative approach, or measurement alternative, which is equal to its cost minus impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for the identical or a similar investment of the same issuer. Our adoption of this standard on October 1, 2018 had no impact on our Consolidated Financial Statements.

In January 2017, the FASB issued Accounting Standard Update No. 2017-01, Business Combinations. This standard clarifies the definition of a business to assist entities with evaluation of whether transactions should be accounted for as acquisitions or disposals of assets or businesses. Our adoption of this standard on October 1, 2018 using the prospective transition method had no impact on our Condensed Consolidated Financial Statements.