During the year ended December 31, 2021, a decrease in stock compensation expenses of $8,617,800, was offset by an increase in professional services of $5,992,100, an increase in personnel and recruiting expenses totaling $1,552,700, and an increase in insurance expense of $476,200.
The decrease in stock compensation expense was driven by the June 2020 common stock issuances of 722,000 shares to our Chief Financial Officer, and Chief Strategy and Innovation Officer which resulted in $9,386,000 of non-recurring stock compensation expenses. The remaining offsetting balance is mainly driven by increased stock compensation expense during the year ended December 31, 2021 from stock grant modifications.
The increase in professional services were impacted primarily by increased legal fees of $4,105,300, increase in corporate finance and development fees of $312,400, and remaining increase driven by professional audit fees. Between October 1, 2021 and December 31, 2021, we incurred $3,147,900 in legal fees and other professional services directly attributed to the Internal Review and related matters. During that same period, we incurred $427,200 in accounting professional fees directly related to the Internal Review. These elevated legal, accounting, and other related professional services expenses are continuing through the date of this report, and are expected continue thereafter.
Personnel and recruiting expenses were impacted by increases to average headcount, and employee salary rates. During the twelve months December 31, 2021 and 2020, the average headcount for employees allocated to general and administrative purposes increased to 11.5 employees from 4.5 employees, respectively. This resulted in increases in salaries, wages, payroll taxes, and benefits totaling $1,297,800. The remaining difference was driven by recruiting expenses for all head count increases across the organization.
Impairment expense. Impairment expense was $430,000 and $0 for the years ended December 31, 2021 and 2020, respectively. As of December 31, 2021, we assessed events and circumstances under ASC 350, which caused us to incur an impairment expense on our Goodwill. The impairment was primarily related to a reduced stock price as of December 31, 2021, which resulted in the carrying value of our equity exceeding the market value of our equity. After analyzing this quantitative circumstance along with other qualitative considerations, we determined to incur impairment expense for the entire balance of our Goodwill.
Gain on loan extinguishment. Gain on loan extinguishment was $105,800 and $0 for the years ended December 31, 2021 and 2020, respectively. During the year ended December 31, 2020, we applied for forgiveness of the SBA Loan in accordance with the terms of the Coronavirus Aid Relief and Economic Security Act (the “CARES Act”). On February 16, 2021 the SBA granted forgiveness of the SBA Loan and all applicable interest. On the date of forgiveness, the principal and accrued interest totaled $105,800.
Other income. Other income was $53,400 and $0 for the years ended December 31, 2021 and 2020, respectively. The increase is entirely driven by service billings from our bioinformatics employees to large academic institutions. The bioinformatics employees joined us in July 2021 as part of the InSilico acquisition. The contracts whereby these billings were generated is not considered part of our ordinary course of business.
Interest expense. Interest expense was $12,200 and $3,300 for the year ended December 31, 2021 and 2020, respectively. The increase is entirely driven by cash paid for interest attributed to the financing arrangement for our Director and Officer Insurance policy. In November 2020, the Company entered into a financing arrangement for its Director and Officer Insurance policy. The total amount financed was approximately $540,500 with an annual interest rate of 4.59%, to be paid over a period of nine months. As of December 31, 2021, this financing arrangement was paid in its entirety.
In November 2021, the Company entered into a financing arrangement for its Director and Officer Insurance policy. The total amount financed was approximately $665,900 with an annual interest rate of 4.59%, to be paid over a period of ten months. As of December 31, 2021, the remaining payable balance on the financed amount was $454,500.
Net loss. As a result of the cumulative effect of the factors described above, our net loss increased to $25,588,700 during the year ended December 31, 2021 compared to $19,200,200 during the year ended December 31, 2020.