Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2024

Summary of Significant Accounting Policies

Summary of allowance for doubtful accounts

The following table reflects the activity in our allowance for doubtful accounts of trade receivables for the year ended December 31 (in millions):

	2024		2023
Balance as of January 1	$	30	$	26
Additions charged to expense		65		53
Accounts written-off, net of recoveries		(55)		(58)
Acquisitions, divestitures and other, net		125		9
Balance as of December 31	$	165	$	30

Schedule of estimated useful lives

The estimated useful lives for significant property and equipment categories are as follows (in years):

	Useful Lives
Vehicles — excluding rail haul cars	3 to 10
Vehicles — rail haul cars	10 to 30
Machinery and equipment (a)	3 to 30
Buildings and improvements	5 to 40
Furniture, fixtures and office equipment	3 to 10

(a) Includes recycling and renewable natural gas (“RNG”) facilities and WM Healthcare Solutions autoclaves and incinerators as well as containers.

Summary of investments in unconsolidated entities

	2024		2023
Equity method investments	$	86	$	538
Investments qualifying for proportional amortization method (a)		707		—
Investments without readily determinable fair values		53		68
Investments in unconsolidated entities	$	846	$	606

(a) As discussed above, our low-income housing investments are accounted for using the proportional amortization method. Prior to 2024, these investments were included as equity method investments.

Schedule of Supplemental Cash Flow Information

	2024		2023		2022
Interest, net of capitalized interest	$	530	$	447	$	348
Income taxes		656		636		736
Accrued capital expenditures		620		508		564