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Stock-based compensation expense relating to the EIP, SDP and RSAP totaled $3.29 million in 2020, $2.76 million in 2019, and $3.55 million in 2018. The total income tax benefit recognized in the accompanying Consolidated Statements of Income related to stock-based compensation was $0.77 million in 2020, $0.65 million in 2019, and $0.86 million in 2018. Unrecognized stock-based compensation expense related to non-vested stock awards (EIP/SDP/RSAP) was $7.63 million at December 31, 2020. At such date, the weighted-average period over which this unrecognized expense was expected to be recognized was 3.44 years. 

The fair value of non-vested stock awards for the purposes of recognizing stock-based compensation expense is market price of the stock on the measurement date, which, for the Company’s purposes is the date of the award. 

Employee Stock Purchase Plan  — The Company offers an ESPP for substantially all employees with at least two years of service on the effective date of an offering under the plan. Eligible employees may elect to purchase any dollar amount of stock, so long as such amount does not exceed 25% of their base rate of pay and the aggregate stock accrual rate for all offerings does not exceed $25,000 in any calendar year. The purchase price for shares offered is the lower of the closing market bid price for the offering date or the average market bid price for the five business days preceding the offering date. The purchase price and premium/(discount) to the actual market closing price on the offering date for the 2020, 2019, and 2018 offerings were $34.35 (1.78%), $43.81 (0.14%), and $53.84 (-0.09%), respectively. Payment for the stock is made through payroll deductions over the offering period, and employees may discontinue the deductions at any time and exercise the option or take the funds out of the program. The most recent offering began June 1, 2020 and runs through June 1, 2022, with $304,635 in stock value to be purchased at $34.35 per share. 

## Note 17 — Income Taxes 

The following table shows the composition of income tax expense. 

<img src='content_image/1038340.jpg'>

The following table shows the reasons for the difference between income tax expense and the amount computed by applying the statutory federal income tax rate (21%) to income before income taxes. 

<img src='content_image/1038341.jpg'>

The tax expense related to gains (losses) on investment securities available-for-sale for the years 2020, 2019, and 2018 was approximately $67,000, $0, and $(83,000), respectively. 

