Note 8. Leases

Operating Leases

The Company leases various office and research and development facilities under operating lease agreements that expire at various dates through October 2050. Under the terms of the agreements, the Company is responsible for certain insurance, property taxes and maintenance expenses. The Company recognizes rent expense on a straight-line basis over the term of the operating leases. Any difference between cash payments required and rent expense is recorded as deferred rent. Rent expense for the three and nine months ended September 30, 2021 was $1.5 million and $4.1 million and $1.3 million and $3.5 million for the three and nine months ended September 30, 2020, respectively.

Capital Leases

The Company purchased equipment with total gross book value of $4.1 million under capital lease agreements. Interest rates for the capital leases range from 3.95% to 22.10% per annum. Accumulated depreciation for equipment acquired under the capital leases was $0.9 million and $0.7 million as of September 30, 2021 and December 31, 2020, respectively.