Property, Plant and Equipment Disclosure
Asset Age Ratios (Summary)
Average Age
Estimated Total Useful Life
Estimated Age, Time Elapsed Since Purchase
Estimated Remaining Life

Biogen Inc., balance sheet: property, plant and equipment

US$ in thousands

	Dec 31, 2021	Dec 31, 2020	Dec 31, 2019	Dec 31, 2018	Dec 31, 2017
Land	207,500)	119,800)	118,100)	144,500)	141,200)
Buildings	1,699,700)	1,025,300)	835,000)	1,282,800)	1,213,600)
Leasehold improvements	121,000)	104,600)	99,500)	94,400)	80,600)
Machinery and equipment	1,585,500)	1,027,800)	844,500)	1,258,100)	1,207,700)
Computer software and hardware	971,600)	903,000)	798,400)	798,700)	767,100)
Furniture and fixtures	67,400)	62,500)	58,300)	61,600)	55,300)
Construction in progress	770,300)	1,950,800)	2,084,400)	1,758,500)	1,276,000)
Property, plant and equipment, cost	5,423,000)	5,193,800)	4,838,200)	5,398,600)	4,741,500)
Accumulated depreciation	(2,006,600)	(1,782,300)	(1,590,900)	(1,797,400)	(1,559,100)
Property, plant and equipment, net	3,416,400)	3,411,500)	3,247,300)	3,601,200)	3,182,400)

Based on: 10-K (reporting date: 2021-12-31), 10-K (reporting date: 2020-12-31), 10-K (reporting date: 2019-12-31), 10-K (reporting date: 2018-12-31), 10-K (reporting date: 2017-12-31).

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Item	Description	The company
Property, plant and equipment, cost	Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.	Biogen Inc. property, plant and equipment, cost increased from 2019 to 2020 and from 2020 to 2021.
Property, plant and equipment, net	Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.	Biogen Inc. property, plant and equipment, net increased from 2019 to 2020 and from 2020 to 2021.

Biogen Inc., asset age ratios

	Dec 31, 2021	Dec 31, 2020	Dec 31, 2019	Dec 31, 2018	Dec 31, 2017
Average age ratio	38.47%	35.13%	33.70%	34.21%	33.89%
Estimated total useful life (years)	22	25	25	20	17
Estimated age, time elapsed since purchase (years)	9	9	8	7	6
Estimated remaining life (years)	14	16	16	13	11

Based on: 10-K (reporting date: 2021-12-31), 10-K (reporting date: 2020-12-31), 10-K (reporting date: 2019-12-31), 10-K (reporting date: 2018-12-31), 10-K (reporting date: 2017-12-31).

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Asset age ratio	Description	The company
Average age ratio	As long as straight-line depreciation is used, this is an accurate estimate of asset age as a percentage of depreciable life. The relative age is a useful measure of whether the company fixed asset base is old or new. Newer assets are likely to be more efficient.	Biogen Inc. average age ratio of depreciable property, plant and equipment deteriorated from 2019 to 2020 and from 2020 to 2021.
Estimated total useful life	Over longer time periods, this ratio is a useful measure of company depreciation policy and can be used for comparisons with competitors.	Biogen Inc. estimated total useful life of depreciable property, plant and equipment increased from 2019 to 2020 but then decreased significantly from 2020 to 2021.
Estimated time elapsed since purchase	The approximate age in years of a company fixed assets. Useful for comparison purposes.	Biogen Inc. estimated time elapsed since purchase of depreciable property, plant and equipment deteriorated from 2019 to 2020 but then improved from 2020 to 2021 not reaching 2019 level.
Estimated remaining life		Biogen Inc. estimated remaining life of depreciable property, plant and equipment decreased from 2019 to 2020 and from 2020 to 2021.

	Dec 31, 2021	Dec 31, 2020	Dec 31, 2019	Dec 31, 2018	Dec 31, 2017
Selected Financial Data (US$ in thousands)
Accumulated depreciation	2,006,600)	1,782,300)	1,590,900)	1,797,400)	1,559,100)
Property, plant and equipment, cost	5,423,000)	5,193,800)	4,838,200)	5,398,600)	4,741,500)
Land	207,500)	119,800)	118,100)	144,500)	141,200)
Asset Age Ratio
Average age¹	38.47%	35.13%	33.70%	34.21%	33.89%

Based on: 10-K (reporting date: 2021-12-31), 10-K (reporting date: 2020-12-31), 10-K (reporting date: 2019-12-31), 10-K (reporting date: 2018-12-31), 10-K (reporting date: 2017-12-31).

2021 Calculations

¹ Average age = 100 × Accumulated depreciation ÷ (Property, plant and equipment, cost – Land)
= 100 × 2,006,600 ÷ (5,423,000 – 207,500) = 38.47%

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Asset age ratio	Description	The company
Average age	As long as straight-line depreciation is used, this is an accurate estimate of asset age as a percentage of depreciable life. The relative age is a useful measure of whether the company fixed asset base is old or new. Newer assets are likely to be more efficient.	Biogen Inc. average age ratio of depreciable property, plant and equipment deteriorated from 2019 to 2020 and from 2020 to 2021.

	Dec 31, 2021	Dec 31, 2020	Dec 31, 2019	Dec 31, 2018	Dec 31, 2017
Selected Financial Data (US$ in thousands)
Property, plant and equipment, cost	5,423,000)	5,193,800)	4,838,200)	5,398,600)	4,741,500)
Land	207,500)	119,800)	118,100)	144,500)	141,200)
Depreciation expense	235,300)	201,900)	190,600)	269,400)	266,300)
Asset Age Ratio (Years)
Estimated total useful life¹	22	25	25	20	17

Based on: 10-K (reporting date: 2021-12-31), 10-K (reporting date: 2020-12-31), 10-K (reporting date: 2019-12-31), 10-K (reporting date: 2018-12-31), 10-K (reporting date: 2017-12-31).

2021 Calculations

¹ Estimated total useful life = (Property, plant and equipment, cost – Land) ÷ Depreciation expense
= (5,423,000 – 207,500) ÷ 235,300 = 22

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Asset age ratio	Description	The company
Estimated total useful life	Over longer time periods, this ratio is a useful measure of company depreciation policy and can be used for comparisons with competitors.	Biogen Inc. estimated total useful life of depreciable property, plant and equipment increased from 2019 to 2020 but then decreased significantly from 2020 to 2021.

	Dec 31, 2021	Dec 31, 2020	Dec 31, 2019	Dec 31, 2018	Dec 31, 2017
Selected Financial Data (US$ in thousands)
Accumulated depreciation	2,006,600)	1,782,300)	1,590,900)	1,797,400)	1,559,100)
Depreciation expense	235,300)	201,900)	190,600)	269,400)	266,300)
Asset Age Ratio (Years)
Time elapsed since purchase¹	9	9	8	7	6

Based on: 10-K (reporting date: 2021-12-31), 10-K (reporting date: 2020-12-31), 10-K (reporting date: 2019-12-31), 10-K (reporting date: 2018-12-31), 10-K (reporting date: 2017-12-31).

2021 Calculations

¹ Time elapsed since purchase = Accumulated depreciation ÷ Depreciation expense
= 2,006,600 ÷ 235,300 = 9

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Asset age ratio	Description	The company
Estimated time elapsed since purchase	The approximate age in years of a company fixed assets. Useful for comparison purposes.	Biogen Inc. estimated time elapsed since purchase of depreciable property, plant and equipment deteriorated from 2019 to 2020 but then improved from 2020 to 2021 not reaching 2019 level.

	Dec 31, 2021	Dec 31, 2020	Dec 31, 2019	Dec 31, 2018	Dec 31, 2017
Selected Financial Data (US$ in thousands)
Property, plant and equipment, net	3,416,400)	3,411,500)	3,247,300)	3,601,200)	3,182,400)
Land	207,500)	119,800)	118,100)	144,500)	141,200)
Depreciation expense	235,300)	201,900)	190,600)	269,400)	266,300)
Asset Age Ratio (Years)
Estimated remaining life¹	14	16	16	13	11

Based on: 10-K (reporting date: 2021-12-31), 10-K (reporting date: 2020-12-31), 10-K (reporting date: 2019-12-31), 10-K (reporting date: 2018-12-31), 10-K (reporting date: 2017-12-31).

2021 Calculations

¹ Estimated remaining life = (Property, plant and equipment, net – Land) ÷ Depreciation expense
= (3,416,400 – 207,500) ÷ 235,300 = 14

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Asset age ratio	Description	The company
Estimated remaining life		Biogen Inc. estimated remaining life of depreciable property, plant and equipment decreased from 2019 to 2020 and from 2020 to 2021.

Biogen Inc. (NASDAQ:BIIB)

Analysis of Property, Plant and Equipment

Property, Plant and Equipment Disclosure

Asset Age Ratios (Summary)

Average Age

Estimated Total Useful Life

Estimated Age, Time Elapsed since Purchase

Estimated Remaining Life