Employee Benefit Plans	12 Months Ended
Dec. 31, 2018
Employee Benefit Plans
Employee Benefit Plans	Note 23: Employee Benefit Plans Old Second Bancorp, Inc. Employees 401(k) Savings Plan and Trust The Company sponsors a qualified, tax-exempt defined contribution plan (the “401(k) Plan”) qualifying under section 401(k) of the Internal Revenue Code. Virtually all employees are eligible to participate after meeting certain age and service requirements. Eligible employees are permitted to contribute up to a dollar limit set by law of their compensation to the 401(k) Plan. For the year ended December 31, 2018, the Company made a discretionary match equal to 100% of the first 3% and 50% of the next 2% to participants of the 401(k) Plan. For the years ended December 31, 2017 and 2016, the Company made a discretionary match equal to 100% of first 3% contributed by participants of the 401(k) Plan. Participants are 100% vested in the discretionary matching contributions. Participants can choose between several different investment options under the 401(k) Plan, including shares of the Company’s common stock. An additional component of the 401(k) Plan arrangement allows the Company to make annual discretionary profit sharing contributions based on the Company’s profitability in a given year, and on each participant’s annual compensation. The Company elected not to make a discretionary profit sharing contribution for the years end December 31, 2018, 2017 and 2016. The total expense relating to the 401(k) Plan was approximately $1.1 million, $785,000 and $698,000 in 2018, 2017 and 2016, respectively. Old Second Bancorp, Inc. Voluntary Deferred Compensation Plan for Executives The Company sponsors an executive deferred compensation plan, which is a means by which certain executives may voluntarily defer a portion of their salary or bonus. This plan is an unfunded, nonqualified deferred compensation arrangement. Company obligations under this arrangement as of both December 31, 2018 and 2017 totaled $2.2 million and totaled $1.6 million as of December 31, 2016, and are included in other liabilities.

Note 23: Employee Benefit Plans

Old Second Bancorp, Inc. Employees 401(k) Savings Plan and Trust

The Company sponsors a qualified, tax-exempt defined contribution plan (the “401(k) Plan”) qualifying under section 401(k) of the Internal Revenue Code. Virtually all employees are eligible to participate after meeting certain age and service requirements. Eligible employees are permitted to contribute up to a dollar limit set by law of their compensation to the 401(k) Plan. For the year ended December 31, 2018, the Company made a discretionary match equal to 100% of the first 3% and 50% of the next 2% to participants of the 401(k) Plan. For the years ended December 31, 2017 and 2016, the Company made a discretionary match equal to 100% of first 3% contributed by participants of the 401(k) Plan. Participants are 100% vested in the discretionary matching contributions. Participants can choose between several different investment options under the 401(k) Plan, including shares of the Company’s common stock. An additional component of the 401(k) Plan arrangement allows the Company to make annual discretionary profit sharing contributions based on the Company’s profitability in a given year, and on each participant’s annual compensation. The Company elected not to make a discretionary profit sharing contribution for the years end December 31, 2018, 2017 and 2016.

The total expense relating to the 401(k) Plan was approximately $1.1 million, $785,000 and $698,000 in 2018, 2017 and 2016, respectively.

Old Second Bancorp, Inc. Voluntary Deferred Compensation Plan for Executives

The Company sponsors an executive deferred compensation plan, which is a means by which certain executives may voluntarily defer a portion of their salary or bonus. This plan is an unfunded, nonqualified deferred compensation arrangement. Company obligations under this arrangement as of both December 31, 2018 and 2017 totaled $2.2 million and totaled $1.6 million as of December 31, 2016, and are included in other liabilities.