Intangible Assets

Indefinite-Lived Intangible Assets

Our indefinite-lived intangible assets consist of FCC licenses, which were acquired primarily through FCC auctions and business combinations, certain of our trademarks and goodwill. At September 30, 2018, we held 800 MHz, 1.9 GHz and 2.5 GHz FCC licenses authorizing the use of radio frequency spectrum to deploy our wireless services. As long as the Company acts within the requirements and constraints of the regulatory authorities, the renewal and extension of these licenses is reasonably certain at minimal cost. Accordingly, we have concluded that FCC licenses are indefinite-lived intangible assets. Our Sprint and Boost Mobile trademarks have also been identified as indefinite-lived intangible assets. Goodwill represents the excess of consideration paid over the estimated fair value of net tangible and identifiable intangible assets acquired in business combinations.

The following provides the activity of indefinite-lived intangible assets within the consolidated balance sheets:



	March 31, 2018		Net Additions		September 30, 2018
	(in millions)
FCC licenses	$	37,274	$	64	$	37,338
Trademarks	4,035		—		4,035
Goodwill⁽¹⁾	6,586		12		6,598
	$	47,895	$	76	$	47,971

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(1)	Through September 30, 2018, there is no accumulated impairment losses for goodwill.

Assessment of Impairment

Our annual impairment testing date for goodwill and indefinite-lived intangible assets is January 1 of each year; however, we test for impairment between our annual tests if an event occurs or circumstances change that indicate that the asset may be impaired, or in the case of goodwill, that the fair value of the reporting unit is below its carrying amount. Our most recent test for impairment of goodwill was completed at June 30, 2018 and we concluded that the estimated fair value of the Wireless reporting unit exceeded the carrying amount. As a result, no goodwill impairment was recorded.

The determination of fair value requires considerable judgment and is highly sensitive to changes in underlying assumptions. Consequently, there can be no assurance that the estimates and assumptions made for the purposes of the goodwill, spectrum licenses, and Sprint and Boost Mobile trade names impairment tests will prove to be an accurate prediction of the future. Sustained declines in the Company’s operating results, number of wireless subscribers, future forecasted cash flows, growth rates and other assumptions, as well as significant, sustained declines in the Company’s stock price and related market capitalization could impact the underlying key assumptions and our estimated fair values, potentially leading to a future material impairment of goodwill or other indefinite-lived intangible assets.

Intangible Assets Subject to Amortization

Customer relationships are amortized using the sum-of-the-months' digits method, while all other definite-lived intangible assets are amortized using the straight-line method over the estimated useful lives of the respective assets. We reduce the gross carrying value and associated accumulated amortization when specified intangible assets become fully amortized. Amortization expense related to favorable spectrum and tower leases is recognized in "Cost of services" in our consolidated statements of comprehensive income (loss).



		September 30, 2018							March 31, 2018
	Useful Lives	Gross Carrying Value		Accumulated Amortization			Net Carrying Value		Gross Carrying Value		Accumulated Amortization			Net Carrying Value
		(in millions)
Customer relationships	5 to 8 years	$	6,563	$	(5,771	)	$	792	$	6,562	$	(5,462	)	$	1,100
Other intangible assets:
Favorable spectrum leases	23 years	767		(135		)	632		856		(172		)	684
Favorable tower leases	7 years	335		(197		)	138		335		(179		)	156
Trademarks	2 to 34 years	520		(82		)	438		520		(74		)	446
Other	5 to 10 years	133		(58		)	75		129		(50		)	79
Total other intangible assets		1,755		(472		)	1,283		1,840		(475		)	1,365
Total definite-lived intangible assets		$	8,318	$	(6,243	)	$	2,075	$	8,402	$	(5,937	)	$	2,465