The following table is a summary of changes in our allowance for doubtful accounts for the years ended December 31, 2022 and 2021.


years ended December 31 (in millions)	2022		2021
Balance at beginning of period	$	122	$	125
Acquisition	—		13
Charged to costs and expenses	7		(2)
Write-offs	(7)		(5)
Currency translation adjustments	(8)		(9)
Balance at end of period	$	114	$	122

Inventories


as of December 31 (in millions)	2022		2021
Raw materials	$	738	$	591
Work in process	293		300
Finished goods	1,687		1,562
Inventories	$	2,718	$	2,453

Prepaid Expenses and Other Current Assets


as of December 31 (in millions)	2022		2021
Prepaid value added taxes	$	189	$	199
Prepaid income taxes	185		166
Contract assets	93		84
Assets held for sale	50		—
Other	399		390
Prepaid expenses and other current assets	$	916	$	839

In September 2022, we signed a purchase agreement with a buyer to sell our corporate headquarters in Deerfield, Illinois for $52 million. The related assets are classified as held for sale and are presented within prepaid expenses and other current assets in the accompanying consolidated balance sheet as of December 31, 2022. While the closing remains subject to the satisfaction of various closing conditions (including satisfactory completion of municipal diligence by the buyer), we expect the transaction to close in 2023. The net book value of the assets approximates the transaction price net of estimated selling costs.

Property, Plant and Equipment, Net


as of December 31 (in millions)	2022		2021
Land and land improvements	$	149	$	172
Buildings and leasehold improvements	1,808		1,915
Machinery and equipment	6,854		7,097
Equipment on lease with customers	1,610		1,684
Construction in progress	1,000		860
Total property, plant and equipment, at cost	11,421		11,728
Accumulated depreciation	(6,442)		(6,550)
Property, plant and equipment, net	$	4,979	$	5,178

Other Non-Current Assets


as of December 31 (in millions)	2022		2021
Deferred tax assets	$	280	$	376
Non-current receivables, net	89		113
Contract assets	122		111
Capitalized implementation costs in hosting arrangements	119		99
Pension and other postretirement benefits	123		228
Investments	247		195
Other	131		91
Other non-current assets	$	1,111	$	1,213

Accrued Expenses and Other Current Liabilities


as of December 31 (in millions)	2022		2021

Common stock dividends payable	$	146	$	140
Employee compensation and withholdings	418		608
Property, payroll and certain other taxes	163		174
Contract liabilities	164		162
Restructuring liabilities	100		97
Accrued rebates	257		312
Operating lease liabilities	121		128
Income taxes payable	91		90
Pension and other postretirement benefits	49		46
Contingent payments related to acquisitions	34		21
Other	659		701
Accrued expenses and other current liabilities	$	2,202	$	2,479

Other Non-Current Liabilities


as of December 31 (in millions)	2022		2021
Pension and other postretirement benefits	$	879	$	1,052
Deferred tax liabilities	698		962
Long-term tax liabilities	64		80

Contingent payments related to acquisitions	50		122
Contract liabilities	80		84
Litigation and environmental reserves	20		28
Restructuring liabilities	7		12
Other	161		153
Other non-current liabilities	$	1,959	$	2,493

Interest Expense, net


years ended December 31 (in millions)	2022		2021		2020
Interest costs	$	426	$	217	$	162
Interest costs capitalized	(11)		(11)		(9)
Interest expense	415		206		153
Interest income	(20)		(14)		(19)
Interest expense, net	$	395	$	192	$	134

Other (Income) Expense, net


years ended December 31 (in millions)	2022		2021		2020
Foreign exchange (gains) losses, net	$	(3)	$	19	$	49
Change in fair value of marketable equity securities	(8)		7		(13)
Loss on debt extinguishment	—		5		110
Pension settlement and curtailment (gains) losses	(12)		2		46
Pension and other postretirement benefit (gains) losses	(25)		11		(3)
Reclassification of cumulative translation loss to earnings	65		—		—
Other, net	(2)		(3)		1
Other (income) expense, net	$	15	$	41	$	190

We have been winding down our operations in Argentina since early 2021 and we determined that the net assets of the related entities were substantially liquidated during the third quarter of 2022. As a result of that determination, we reclassified their $65 million cumulative translation loss from accumulated other comprehensive income (loss) to other (income) expense, net.

Purchases of property, plant and equipment included in accounts payable and accrued liabilities as of December 31, 2022, 2021 and 2020 was $91 million, $79 million and $102 million, respectively.

Other Supplemental Information


year ended December 31 (in millions)	2022		2021		2020
Interest paid, net of portion capitalized	$	355	$	145	$	137
Income taxes paid	$	330	$	282	$	249