The following tables provide details of selected consolidated balance sheet items:

Activity in the allowance for credit losses related to accounts receivable was as follows:


Balance at June 30, 2021	$	800
Charged to expense	238
Write-offs	(183)
Balance at March 31, 2022	$	855

Capitalized internal-use software and accumulated amortization were as follows:


	June 30, 2021		March 31, 2022
Capitalized internal-use software	$	150,922	$	182,140
Accumulated amortization	(105,904)		(124,427)
Capitalized internal-use software, net	$	45,018	$	57,713

Amortization of capitalized internal-use software costs is included in Cost of revenues and amounted to $6,005 and $6,308 for the three months ended March 31, 2021 and 2022, respectively, and $17,273 and $18,523 for the nine months ended March 31, 2021 and 2022, respectively.


	June 30, 2021		March 31, 2022
Office equipment	$	5,211	$	4,365
Computer equipment	45,420		54,172
Furniture and fixtures	13,104		12,791
Software	6,641		8,278
Leasehold improvements	46,814		47,255
Time clocks rented by clients	5,399		6,423
Total	122,589		133,284
Accumulated depreciation	(62,754)		(69,280)
Property and equipment, net	$	59,835	$	64,004

Depreciation expense amounted to $3,966 and $4,098 for the three months ended March 31, 2021 and 2022, respectively, and $11,985 and $11,914 for the nine months ended March 31, 2021 and 2022, respectively.

The following table summarizes changes in goodwill during the nine months ended March 31, 2022:


	March 31, 2022
Balance at June 30, 2021	$	33,650
Additions attributable to acquisitions	68,533
Balance at March 31, 2022	$	102,183

The Company’s amortizable intangible assets and estimated useful lives are as follows:


	June 30, 2021		March 31, 2022		Weighted average useful life (years)
Proprietary technology	$	6,129	$	43,129	6.0
Client relationships	19,200		22,200		7.8
Non-solicitation agreements	1,600		1,600		3.1
Trade names	440		1,640		5.0
Total	27,369		68,569
Accumulated amortization	(14,342)		(20,324)
Intangible assets, net	$	13,027	$	48,245

Amortization expense for acquired intangible assets was $1,028 and $2,630 for the three months ended March 31, 2021 and 2022, respectively, and $2,812 and $5,982 for the nine months ended March 31, 2021 and 2022, respectively.

Future amortization expense for acquired intangible assets as of March 31, 2022 is as follows:


Remainder of fiscal 2022	$	2,770
Fiscal 2023	10,948
Fiscal 2024	9,943
Fiscal 2025	8,888
Fiscal 2026	7,269
Thereafter	8,427
Total	$	48,245


	June 30, 2021		March 31, 2022
Accrued payroll and personnel costs	$	73,969	$	67,965
Operating lease liabilities	7,549		8,270
Deferred revenue	9,442		14,326
Other	12,149		18,259
Total accrued expenses	$	103,109	$	108,820