The changes in the carrying amount of goodwill for the years ended December 31, 2021 and 2020 are as follows (in millions):

Balance, beginning balance	2021			2020
Goodwill	$	7,033		$	7,142
Accumulated impairment losses		(2,814	)		(2,814	)
		4,219			4,328
Goodwill acquired as part of acquisitions during current year		5			1
Goodwill allocated to hospitals divested or held for sale		(5	)		(110	)

Balance, end of year
Goodwill		7,033			7,033
Accumulated impairment losses		(2,814	)		(2,814	)
	$	4,219		$	4,219

Goodwill is allocated to each identified reporting unit, which is defined as an operating segment or one level below the operating segment (referred to as a component of the entity). Management has determined that the Company’s operating segment meets the criteria to be classified as a reporting unit. At December 31, 2021, after giving effect to 2021 acquisition and divestiture activity, the Company had approximately $4.2 billion of goodwill recorded.

Goodwill is evaluated for impairment annually and when an event occurs or circumstances change that, more likely than not, reduce the fair value of the reporting unit below its carrying value. The Company performed its last annual goodwill impairment evaluation during the fourth quarter of 2021 using an October 31, 2021 measurement date, which indicated no impairment.

The Company estimates the fair value of the reporting unit using both a discounted cash flow model as well as a market multiple model. The cash flow forecasts are adjusted by an appropriate discount rate based on the Company’s estimate of a market participant’s weighted-average cost of capital. These models are both based on the Company’s best estimate of future revenues and operating costs

and are reconciled to the Company’s consolidated market capitalization, with consideration of the amount a potential acquirer would be required to pay, in the form of a control premium, in order to gain sufficient ownership to set policies, direct operations and control management decisions.

The determination of fair value in the Company’s goodwill impairment analysis is based on an estimate of fair value for the reporting unit utilizing known and estimated inputs at the evaluation date. Some of those inputs include, but are not limited to, the most recent price of the Company’s common stock and fair value of long-term debt, estimates of future revenue and expense growth, estimated market multiples, expected capital expenditures, income tax rates, and costs of invested capital. A detailed evaluation of potential impairment indicators was performed as of December 31, 2021, which specifically considered the volatility of the fair market value of the Company’s outstanding senior secured and unsecured notes and common stock during the year ended December 31, 2021. On the basis of available evidence as of December 31, 2021, no indicators of impairment were identified.

Future estimates of fair value could be adversely affected if the actual outcome of one or more of the assumptions described above changes materially in the future, including a decline in the Company’s stock price and the fair value of its long-term debt, an increase in the volatility of the Company’s stock price and the fair value of its long-term debt, lower than expected hospital volumes and/or net operating revenues, higher market interest rates or increased operating costs. Such changes impacting the calculation of fair value, the risks of which may be amplified by the COVID-19 pandemic, could result in a material impairment charge in the future.

The determination of fair value of the Company’s hospital operations reporting unit as part of its goodwill impairment measurement represents a Level 3 fair value measurement in the fair value hierarchy due to its use of internal projections and unobservable measurement inputs.

No intangible assets other than goodwill were acquired during the years ended December 31, 2021 and 2020. The gross carrying amount of the Company’s other intangible assets subject to amortization was $1 million at both December 31, 2021 and 2020, and the net carrying amount was less than $1 million at both December 31, 2021 and 2020. The carrying amount of the Company’s other intangible assets not subject to amortization was $54 million and $53 million at December 31, 2021 and 2020, respectively. Other intangible assets are included in other assets, net on the Company’s consolidated balance sheets. Substantially all of the Company’s intangible assets are contract-based intangible assets related to operating licenses, management contracts, or non-compete agreements entered into in connection with prior acquisitions.

The weighted-average remaining amortization period for the intangible assets subject to amortization is approximately three years. There are no expected residual values related to these intangible assets. Amortization expense on these intangible assets was less than $1 million, less than $1 million and $1 million during the years ended December 31, 2021, 2020 and 2019, respectively. Amortization expense on intangible assets is estimated to be less than $1 million in 2022.

The gross carrying amount of capitalized software for internal use was approximately $992 million and $1.1 billion at December 31, 2021 and 2020, respectively, and the net carrying amount was approximately $215 million and $251 million at December 31, 2021 and 2020, respectively. The estimated amortization period for capitalized internal-use software is generally three years. There is no expected residual value for capitalized internal-use software. At December 31, 2021, there were approximately $79 million of capitalized costs for internal-use software that is currently in the development stage and will begin amortization once the software project is complete and ready for its intended use. Amortization expense on capitalized internal-use software was $108 million, $123 million and $121 million during the years ended December 31, 2021, 2020 and 2019, respectively. Amortization expense on capitalized internal-use software is estimated to be $90 million in 2022, $62 million in 2023, $40 million in 2024, $9 million in 2025, $7 million in 2026 and $7 million thereafter.