Summary of Significant Accounting Policies	9 Months Ended
Sep. 30, 2017
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	Note 1 – Summary of Significant Accounting Policies The accounting policies followed in the preparation of the interim consolidated financial statements are consistent with those used in the preparation of the annual financial information. The interim consolidated financial statements reflect all normal and recurring adjustments that are necessary, in the opinion of management, for a fair statement of results for the interim period presented. Results for the period ended September 30, 2017, are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. These interim consolidated financial statements are unaudited and should be read in conjunction with the audited financial statements and notes included in Old Second Bancorp, Inc.’s (the “Company”) annual report on Form 10-K for the year ended December 31, 2016. Unless otherwise indicated, amounts in the tables contained in the notes to the consolidated financial statements are in thousands. Certain items in prior periods have been reclassified to conform to the current presentation. The Company’s consolidated financial statements are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and follow general practices within the banking industry. Application of these principles requires management to make estimates, assumptions, and judgments that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates, assumptions, and judgments are based on information available as of the date of the consolidated financial statements. Future changes in information may affect these estimates, assumptions, and judgments, which, in turn, may affect amounts reported in the consolidated financial statements. All significant accounting policies are presented in Note 1 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016. These policies, along with the disclosures presented in the other financial statement notes and in this discussion, provide information on how significant assets and liabilities are valued in the consolidated financial statements and how those values are determined. Recent Accounting Pronouncements In May 2014, the FASB issued ASU No. 2014-09 "Revenue from Contracts with Customers (Topic 606)." The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. In August 2015, the FASB issued ASU 2015-14 “Revenue from Contracts with Customers (Topic 606) Deferral of the Effective Date.” This accounting standards update defers the effective date of ASU 2014-09 for an additional year. ASU 2015-14 will be effective for annual reporting periods beginning after December 15, 2017. The amendments can be applied retrospectively to each prior reporting period or retrospectively with the cumulative effect of initially applying this update recognized at the date of initial application. Early application is not permitted. In March 2016, the FASB issued ASU 2016-08 “Revenue from Contracts with Customers (TOPIC 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net)” and in April 2016, the FASB issued ASU 2016-10 “Revenue from Contracts with Customers (TOPIC 606): Identifying Performance Obligations and Licensing.” ASU 2016-08 requires the entity to determine if it is acting as a principal with control over the goods or services it is contractually obligated to provide, or an agent with no control over specified goods or services provided by another party to a customer. ASU 2016-10 was issued to further clarify ASU 2014-09 implementation regarding identifying performance obligation materiality, identification of key contract components, and scope. The Company is assessing the impact of ASU 2014-09 and other related ASUs as noted above on its accounting and disclosures within noninterest income, as any interest income impact was not included in the scope of this final ASU pronouncement. Adoption of this ASU is expected to affect the methodology used to record certain recurring revenue streams within trust and asset management fees, but this impact is not anticipated to be significant to the Company’s financial statements. The Company will adopt ASU 2015-14 and related issuances on January 1, 2018, with a cumulative effect adjustment to opening retained earnings, if an adjustment is deemed to be material. In February 2016, the FASB issued ASU No. 2016-02 “Leases (Topic 842).” This ASU was issued to increase transparency and comparability among organizations by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. One key revision from prior guidance was to include operating leases within assets and liabilities recorded; another revision was included which created a new model to follow for sale-leaseback transactions. The impact of this pronouncement will affect lessees primarily, as virtually all of their assets will be recognized on the balance sheet, by recording a right of use asset and lease liability. This pronouncement is effective for fiscal years beginning after December 15, 2018. The Company is assessing the impact of ASU 2016-02 on its accounting and disclosures. In March 2016, the FASB issued ASU No. 2016-09 “Stock Compensation - Improvements to Employee Share-Based Payment Accounting (Topic 718).” FASB issued this ASU as part of the Simplification Initiative. This ASU involves several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liability, and classification on the statement of cash flows. ASU 2016-09 is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. This standard was adopted by the Company effective January 2017; the adoption of this standard did not have a material effect on the Company’s operating results or financial condition. In June 2016, the FASB issued ASU No. 2016-13 “Measurement of Credit Losses on Financial Instruments (Topic 326).” ASU 2016-13 was issued to provide financial statement users with more useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date to enhance the decision making process. The new methodology to be used should reflect expected credit losses based on relevant vintage historical information, supported by reasonable forecasts of projected loss given defaults, which will affect the collectability of the reported amounts. This new methodology will also require available-for-sale debt securities to have a credit loss recorded through an allowance rather than write-downs. ASU 2016-13 is effective for financial statements issued for fiscal years beginning after December 15, 2019. The Company is assessing the impact of ASU 2016-13 on its accounting and disclosures, and is in the process of accumulating data and evaluating model options to support future risk assessments. In March 2017, the FASB issued ASU No. 2017-08 “Receivables-Nonrefundable Fees and Other Costs – Premium Amortization on Purchased Callable Debt Securities (Subtopic 310-20).” This ASU was issued to shorten the amortization period for the premium to the earliest call date on debt securities. This premium is required to be recorded as a reduction to net interest margin during the shorter yield to call period, as compared to prior practice of amortizing the premium as a reduction to net interest margin over the contractual life of the instrument. This ASU does not change the current method of amortizing any discount over the contractual life of the debt security, and this pronouncement is effective for fiscal years beginning after December 15, 2018, with earlier adoption permitted. The Company adopted ASU 2017-08 as a change in accounting principle in the third quarter of 2017 on a modified retrospective basis, which required the Company to reflect its adoption effective January 1, 2017. The effect of amortizing the premium over a shorter period negatively impacted the net interest margin for the first nine months of 2017, and will continue to decrease future quarterly net interest income by approximately 10 basis points a quarter until the premium, which is $25.0 million as of September 30, 2017, is fully amortized. As a result of management’s analysis, the impact of the change in accounting principle as a result of ASU 2017-08 to adjust beginning of year retained earnings was considered insignificant and, accordingly, the impact was adjusted through current period earnings. In August 2017, the FASB issued ASU 2017-12, “Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities”. The purpose of this updated guidance is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. ASU 2017-12 is effective for public business entities for fiscal years beginning after December 15, 2018, with early adoption, including adoption in an interim period, permitted. The Company plans to adopt ASU 2017-12 on January 1, 2018. ASU 2017-12 requires a modified retrospective transition method in which the Company will recognize the cumulative effect of the change on the opening balance of each affected component of equity in the statement of financial position as of the date of adoption. While the Company continues to assess all potential impacts of the standard, we currently expect adoption to have an immaterial impact on our consolidated financial statements. Subsequent Events On October 17, 2017, the Company’s Board of Directors declared a cash dividend of $0.01 per share payable on November 6, 2017, to stockholders of record as of October 27, 2017; dividends of $296,000 were paid to stockholders on November 6, 2017.

Note 1 – Summary of Significant Accounting Policies

The accounting policies followed in the preparation of the interim consolidated financial statements are consistent with those used in the preparation of the annual financial information. The interim consolidated financial statements reflect all normal and recurring adjustments that are necessary, in the opinion of management, for a fair statement of results for the interim period presented. Results for the period ended September 30, 2017, are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. These interim consolidated financial statements are unaudited and should be read in conjunction with the audited financial statements and notes included in Old Second Bancorp, Inc.’s (the “Company”) annual report on Form 10-K for the year ended December 31, 2016. Unless otherwise indicated, amounts in the tables contained in the notes to the consolidated financial statements are in thousands. Certain items in prior periods have been reclassified to conform to the current presentation.

The Company’s consolidated financial statements are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and follow general practices within the banking industry. Application of these principles requires management to make estimates, assumptions, and judgments that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates, assumptions, and judgments are based on information available as of the date of the consolidated financial statements. Future changes in information may affect these estimates, assumptions, and judgments, which, in turn, may affect amounts reported in the consolidated financial statements.

All significant accounting policies are presented in Note 1 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2016. These policies, along with the disclosures presented in the other financial statement notes and in this discussion, provide information on how significant assets and liabilities are valued in the consolidated financial statements and how those values are determined.

Recent Accounting Pronouncements

In May 2014, the FASB issued ASU No. 2014-09 "Revenue from Contracts with Customers (Topic 606)." The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and services. In August 2015, the FASB issued ASU 2015-14 “Revenue from Contracts with Customers (Topic 606) Deferral of the Effective Date.” This accounting standards update defers the effective date of ASU 2014-09 for an additional year. ASU 2015-14 will be effective for annual reporting periods beginning after December 15, 2017. The amendments can be applied retrospectively to each prior reporting period or retrospectively with the cumulative effect of initially applying this update recognized at the date of initial application. Early application is not permitted. In March 2016, the FASB issued ASU 2016-08 “Revenue from Contracts with Customers (TOPIC 606): Principal versus Agent Considerations (Reporting Revenue Gross versus Net)” and in April 2016, the FASB issued ASU 2016-10 “Revenue from Contracts with Customers (TOPIC 606): Identifying Performance Obligations and Licensing.” ASU 2016-08 requires the entity to determine if it is acting as a principal with control over the goods or services it is contractually obligated to provide, or an agent with no control over specified goods or services provided by another party to a customer. ASU 2016-10 was issued to further clarify ASU 2014-09 implementation regarding identifying performance obligation materiality, identification of key contract components, and scope. The Company is assessing the impact of ASU 2014-09 and other related ASUs as noted above on its accounting and disclosures within noninterest income, as any interest income impact was not included in the scope of this final ASU pronouncement. Adoption of this ASU is expected to affect the methodology used to record certain recurring revenue streams within trust and asset management fees, but this impact is not anticipated to be significant to the Company’s financial statements. The Company will adopt ASU 2015-14 and related issuances on January 1, 2018, with a cumulative effect adjustment to opening retained earnings, if an adjustment is deemed to be material.

In February 2016, the FASB issued ASU No. 2016-02 “Leases (Topic 842).” This ASU was issued to increase transparency and comparability among organizations by recognizing lease assets and liabilities on the balance sheet and disclosing key information about leasing arrangements. One key revision from prior guidance was to include operating leases within assets and liabilities recorded; another revision was included which created a new model to follow for sale-leaseback transactions. The impact of this pronouncement will affect lessees primarily, as virtually all of their assets will be recognized on the balance sheet, by recording a right of use asset and lease liability. This pronouncement is effective for fiscal years beginning after December 15, 2018. The Company is assessing the impact of ASU 2016-02 on its accounting and disclosures.

In March 2016, the FASB issued ASU No. 2016-09 “Stock Compensation - Improvements to Employee Share-Based Payment Accounting (Topic 718).” FASB issued this ASU as part of the Simplification Initiative. This ASU involves several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liability, and classification on the statement of cash flows. ASU 2016-09 is effective for financial statements issued for fiscal years beginning after December 15, 2016, and interim periods within those fiscal years. This standard was adopted by the Company effective January 2017; the adoption of this standard did not have a material effect on the Company’s operating results or financial condition.

In June 2016, the FASB issued ASU No. 2016-13 “Measurement of Credit Losses on Financial Instruments (Topic 326).” ASU 2016-13 was issued to provide financial statement users with more useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date to enhance the decision making process. The new methodology to be used should reflect expected credit losses based on relevant vintage historical information, supported by reasonable forecasts of projected loss given defaults, which will affect the collectability of the reported amounts. This new methodology will also require available-for-sale debt securities to have a credit loss recorded through an allowance rather than write-downs. ASU 2016-13 is effective for financial statements issued for fiscal years beginning after December 15, 2019. The Company is assessing the impact of ASU 2016-13 on its accounting and disclosures, and is in the process of accumulating data and evaluating model options to support future risk assessments.

In March 2017, the FASB issued ASU No. 2017-08 “Receivables-Nonrefundable Fees and Other Costs – Premium Amortization on Purchased Callable Debt Securities (Subtopic 310-20).” This ASU was issued to shorten the amortization period for the premium to the earliest call date on debt securities. This premium is required to be recorded as a reduction to net interest margin during the shorter yield to call period, as compared to prior practice of amortizing the premium as a reduction to net interest margin over the contractual life of the instrument. This ASU does not change the current method of amortizing any discount over the contractual life of the debt security, and this pronouncement is effective for fiscal years beginning after December 15, 2018, with earlier adoption permitted. The Company adopted ASU 2017-08 as a change in accounting principle in the third quarter of 2017 on a modified retrospective basis, which required the Company to reflect its adoption effective January 1, 2017. The effect of amortizing the premium over a shorter period negatively impacted the net interest margin for the first nine months of 2017, and will continue to decrease future quarterly net interest income by approximately 10 basis points a quarter until the premium, which is $25.0 million as of September 30, 2017, is fully amortized. As a result of management’s analysis, the impact of the change in accounting principle as a result of ASU 2017-08 to adjust beginning of year retained earnings was considered insignificant and, accordingly, the impact was adjusted through current period earnings.

In August 2017, the FASB issued ASU 2017-12, “Derivatives and Hedging: Targeted Improvements to Accounting for Hedging Activities”. The purpose of this updated guidance is to better align a company’s financial reporting for hedging activities with the economic objectives of those activities. ASU 2017-12 is effective for public business entities for fiscal years beginning after December 15, 2018, with early adoption, including adoption in an interim period, permitted. The Company plans to adopt ASU 2017-12 on January 1, 2018. ASU 2017-12 requires a modified retrospective transition method in which the Company will recognize the cumulative effect of the change on the opening balance of each affected component of equity in the statement of financial position as of the date of adoption. While the Company continues to assess all potential impacts of the standard, we currently expect adoption to have an immaterial impact on our consolidated financial statements.

Subsequent Events

On October 17, 2017, the Company’s Board of Directors declared a cash dividend of $0.01 per share payable on November 6, 2017, to stockholders of record as of October 27, 2017; dividends of $296,000 were paid to stockholders on November 6, 2017.