6.     Property, Plant and Equipment

Property, plant and equipment, including equipment under finance lease obligations and capitalized software development costs, consists of the following:

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For the three months ended September 30, 2022 and September 30, 2021, total depreciation expense was $1.9 million and $2.9 million, respectively. For the nine months ended September 30, 2022 and September 30, 2021, total depreciation expense was $6.6 million and $8.5 million, respectively.

Property and equipment under finance lease obligations, consisting of computer equipment, totaled $12.3 million on September 30, 2022 and December 31, 2021, respectively. As of September 30, 2022 and December 31, 2021, accumulated depreciation related to property and equipment under finance lease obligations totaled $10.9 million and $10.0 million, respectively. Refer to Note 7, Leases.

During the three and nine months ended September 30, 2022, the Company disposed of certain office furniture, equipment and leasehold improvements resulting in a loss on disposal of less than $0.1 million and $1.4 million, respectively. The fixed asset disposals relate primarily to the transfer of fixed assets in a sublease office arrangement and the abandonment of fixed assets no longer in use. The loss on disposal was recorded in General and administrative expenses in the accompanying Condensed Consolidated Statements of Operations and Comprehensive Income.