DETAILS OF CERTAIN BALANCE SHEET ACCOUNTS

Accounts receivable, net:



	March 31,
(in thousands)	2018			2019
Accounts receivable	$	202,270		$	393,415
Provisions for returns	(10,225		)	—			¹
Provisions for promotions and rebates	(38,284		)	(50,789		)	¹
Provisions for doubtful accounts and sales allowances	(873		)	(4,956		)
Accounts receivable, net	$	152,888		$	337,671

⁽¹⁾ Upon adoption of ASC 606, the provision for returns and certain provisions for promotions, rebates and other were reclassified to accrued liabilities as these reserve balances are considered refund liabilities. Refer to Note 3, Recent Accounting Pronouncements, for additional information on the adoption impact.

Inventory, net:



	March 31,
(in thousands)	2018		2019
Raw materials	$	28,789	$	34,054
Work in process	450		274
Finished goods	39,037		142,818
Inventory, net	$	68,276	$	177,146

Property, plant, and equipment, net:



	March 31,
(in thousands)	2018			2019
Land	$	16,564		$	16,418
Buildings and improvements (useful life: 7-30 years)	115,401			138,000
Machinery and equipment (useful life: 2-10 years)	112,719			158,326
Software (useful life: 5-6 years)	50,631			68,985
Construction in progress	5,428			13,099
Property, plant, and equipment, gross	300,743			394,829
Accumulated depreciation and amortization	(158,614		)	(190,002		)
Property, plant, and equipment, net	$	142,129		$	204,826

Depreciation and amortization expense for Fiscal Years 2017, 2018 and 2019 was $20.7 million, $21.1 million, and $40.6 million, respectively.

Included in software are unamortized capitalized software costs relating to both purchased and internally developed software of $23.6 million and $30.6 million at March 31, 2018 and 2019, respectively. Amortization expense related to capitalized software costs in Fiscal Years 2017, 2018, and 2019 was $4.4 million, $4.9 million, and $11.0 million, respectively.

Included in construction in progress at March 31, 2019 was tooling for new products, machinery and equipment, building improvements at our U.S. headquarters, and IT-related expenditures. None of the items were individually material.

Accrued Liabilities:



	March 31,		March 31,
(in thousands)	2018		2019
Short term deferred revenue	$	2,986	$	133,200
Employee compensation and benefits	28,599		68,882
Income tax payable	5,583		5,692
Provision for returns	—		24,632		¹
Marketing incentives liabilities	—		25,369		¹
Discounts reserve	—		46,894		¹
Accrued interest	10,424		10,425
Warranty obligation	7,550		15,736
VAT/Sales tax payable	5,353		11,804
Derivative liabilities	2,947		3,275
Accrued other	16,655		52,806
Accrued liabilities	$	80,097	$	398,715

Changes in the warranty obligation, which are included as a component of accrued liabilities in the consolidated balance sheets, are as follows:



	Year ended March 31,
(in thousands)	2018			2019
Warranty obligation at beginning of year	$	8,697		$	9,604
Polycom warranty obligation ⁽¹⁾	—			9,095
Warranty provision related to products shipped	9,923			19,884
Deductions for warranty claims processed	(10,193		)	(20,638		)
Adjustments related to preexisting warranties	1,177			39
Warranty obligation at end of year ⁽²⁾	$	9,604		$	17,984

⁽¹⁾ Represents warranty obligation assumed upon completion of the Acquisition on July 2, 2018.

⁽²⁾ Includes both short-term and long-term portion of warranty obligation.