We are obligated under non-cancellable operating leases primarily for office space. Rent expense for all operating leases, which includes minimum lease payments and other charges such as common area maintenance fees, charged to operations was $5.6 million, $4.9 million and $5.0 million for the years ended December 31, 2018, 2017 and 2016, respectively.

On December 20, 2017, we executed the fourth amendment to our lease agreement for our current headquarters located in Minneapolis, Minnesota where we lease approximately 189,000 square feet under an agreement that expires on April 30, 2025. We have agreed to expand our headquarters premises by approximately 25,000 square feet during 2020. Our lease agreement also includes a further expansion right and a right of first offer to lease certain additional space and two options to extend the term of the lease for five years at a market rate determined in accordance with the lease. We received $3.2 million in incentives upon execution of the amendment and we are owed an additional $2.1 million in incentives upon expansion of our square footage in 2018, both of which have been incorporated into our deferred rent calculation.

At December 31, 2018, our future minimum payments under operating leases were as follows (in thousands):

2019	$	4,209
2020		3,542
2021		4,414
2022		4,042
2023		3,854
Thereafter		4,817
	$	24,878

We may be involved in various claims and legal actions in the normal course of business. Our management believes that the outcome of any such claims and legal actions will not have a material effect on our financial position, results of operations or cash flows.