UScellular is subject to asset retirement obligations associated with certain cell sites, land, switching offices, retail stores and office locations.

TDS Telecom owns poles, cable and wire and certain buildings and also leases office space and property used for housing central office switching equipment and fiber cable. These assets and leases often have removal or remediation requirements.

Asset retirement obligations are included in Other deferred liabilities and credits in the Consolidated Balance Sheet.

In 2024 and 2023, UScellular and TDS Telecom performed a review of the assumptions and estimated future costs related to asset retirement obligations. The results of the reviews and other changes in asset retirement obligations during 2024 and 2023, were as follows:


	2024		2023
(Dollars in millions)
Balance at beginning of year	$	556	$	524
Additional liabilities accrued	25		10
Revisions in estimated cash outflows	9		(3)

Disposition of assets	(11)		(4)
Accretion expense	29		29

Balance at end of year	$	608	$	556