COMMITMENTS AND CONTINGENCIES BRP Leasing is the indirect obligor under a lease for office space at BRP Holding. See Note 13 for information concerning BRP Leasings minimum annual rental expense. Future minimum annual rental income (exclusive of month-to-month leases, real estate taxes, maintenance and certain other charges) from real estate held for investment are aggregated as follows at December 31, 2017 (in thousands): 2018 $ 4,808 2019 4,003 2020 3,769 2021 3,468 2022 2,849 Thereafter 10,369 $ 29,266 We agreed to indemnify Jefferies for certain lease obligations of BRP Leasing that were assumed from a former subsidiary of Jefferies that was sold to a third party prior to the Acquisition. The former subsidiary of Jefferies remains the primary obligor under the lease obligations and Jefferies agreed to indemnify the third party buyer. The primary lease expires in 2018 and the aggregate amount of lease obligations as of December 31, 2017 was approximately $9,750,000 of which includes approximately $3,450,000 projected operating expenses and taxes related to the real estate. Substantially all of the space under the primary lease has been sublet to various third-party tenants for the full length of the lease term in amounts in excess of the obligations under the primary lease. BRP Leasing is required to keep a minimum of $500,000 on deposit in an escrow account to secure its lease obligations. At December 31, 2017 , $1,400,000 was in the escrow account and is classified as restricted cash. Our corporate office space lease was renewed during 2017 and is leased under a non-cancellable lease that expires in October 2023. Rental expense (net of sublease income) was $250,000 for each of the years ended 2017 , 2016 and 2015 . Under the new lease, we are subject to a 3% escalator each year commencing on November 1, 2018. A portion of this space is leased to Jefferies through October 2018; see Note 13 for more information. Future minimum annual rental (exclusive of month-to-month leases, real estate taxes, maintenance a