Prepaid expenses and other, classified as current assets, included the following:


(in thousands)	December 31, 2021		December 31, 2020
Deposit for FCC spectrum licenses	$	16,118	$	—
Prepaid maintenance expenses	8,391		4,018
Broadband contract acquisition costs	2,502		2,308
SERP investments	801		—
Other	2,018		1,196
Prepaid expenses and other	$	29,830	$	7,522

Deferred charges and other assets, classified as long-term assets, included the following:


(in thousands)	December 31, 2021		December 31, 2020
Broadband contract acquisition costs	$	5,645	$	5,050
Prepaid expenses and other	4,653		1,398
Deferred charges and other assets	$	10,298	$	6,448

Accrued liabilities and other, classified as current liabilities, included the following:


(in thousands)	December 31, 2021		December 31, 2020
Interest rate swaps	$	—	$	4,048
Accrued programming costs	3,084		2,868
Sales and property taxes payable	1,065		1,072
Restructuring accrual	1,761		—
Other current liabilities	8,739		5,881
Accrued liabilities and other	$	14,649	$	13,869

Other liabilities, classified as long-term liabilities, included the following:


(in thousands)	December 31, 2021		December 31, 2020
Noncurrent portion of deferred lease revenue	$	19,749	$	18,687
FCC spectrum license obligations	3,807		3,845
Noncurrent portion of financing leases	1,614		1,492
Other	461		881
Other liabilities	$	25,631	$	24,905

During 2021, in connection with the disposition of our Wireless segment, we implemented a restructuring plan whereby certain employees were notified of their pending dismissal under the workforce reduction program. The following table identifies severance activity that has occurred as a result of the plan:


(in thousands)	Year Ended December 31, 2021
Beginning Balance January 1, 2021	$	—
Expense (1)	3,862
Payments (2)	(2,101)
Ending Balance - December 31, 2021	$	1,761

(1)For the year ended December 31, 2021, approximately $2.2 million of expense was recognized within discontinued operations and $1.7 million in continuing operations.

(2)For the year ended December 31, 2021, approximately $1.4 million of payments were attributable to discontinued operations and $0.7 million in continued operations.

Our asset retirement obligations ("ARO") arise from certain of our leases and generally require us to remove our towers from ground leases. The Company's estimates related to ARO were revised during 2021 resulting in recognition of an additional obligation of $4.3 million. Below is a summary of our current and non-current asset retirement obligations:


	Years Ended December 31,
(in thousands)	2021		2020		2019
Balance at beginning of year	$	5,113	$	6,152	$	8,808
Additional liabilities accrued	4,334		262		593
Changes to prior estimates	(44)		(1,633)		(3,659)
Payments	—		—		—
Accretion expense	421		332		410
Balance at end of year	$	9,824	$	5,113	$	6,152