United states securities and exchange commission

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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)
F- 69
Government Matters
We have learned that state and federal governmental authorities are investigating our sales and promotional 
practices and have received related subpoenas. We are cooperating with the government.
We have received subpoenas and other requests from the federal government for documents and information 
relating to our relationship with non-profit organizations that provide assistance to patients taking drugs sold by 
Biogen and Biogen's co-pay assistance programs. We are cooperating with the government.
On July 1, 2016, we received civil investigative demands from the federal government for documents and 
information relating to our treatment of certain service agreements with wholesalers when calculating and reporting 
Average Manufacturer Prices in connection with the Medicaid Drug Rebate Program. We are cooperating with the 
government.
In July 2017 we learned that the Prosecution Office of Milan is investigating our interactions with certain 
healthcare providers in Italy. We are cooperating with the government.
Product Liability and Other Legal Proceedings
We are also involved in product liability claims and other legal proceedings generally incidental to our normal 
business activities. While the outcome of any of these proceedings cannot be accurately predicted, we do not believe 
the ultimate resolution of any of these existing matters would have a material adverse effect on our business or 
financial condition.
22. 
Commitments and Contingencies
TYSABRI Contingent Payments
In 2013 we acquired from Elan full ownership of all remaining rights to TYSABRI that we did not already own or 
control. Under the acquisition agreement, we are obligated to make contingent payments to Elan of 18% on annual 
worldwide net sales up to $2.0 billion and 25% on annual worldwide net sales that exceed $2.0 billion. Royalty 
payments to Elan and other third parties are recognized as cost of sales in our consolidated statements of income. 
Elan was acquired by Perrigo Company plc (Perrigo) in December 2013, and Perrigo subsequently sold its rights to 
these payments to a third party effective January 2017.
Contingent Consideration related to Business Combinations
In connection with our acquisitions of Convergence, Stromedix and BIN, we agreed to make additional 
payments based upon the achievement of certain milestone events. 
As the acquisitions of Convergence, Stromedix and BIN, occurred after January 1, 2009, we recorded the 
contingent consideration liabilities associated with these transactions at their fair value on the acquisition date and 
revalue these obligations each reporting period. We may pay up to approximately $1.1 billion in remaining 
milestones related to these acquisitions. For additional information on our acquisition of Convergence please read 
Note 2, Acquisitions, to these consolidated financial statements.
Fumapharm AG
In 2006 we acquired Fumapharm AG. As part of this acquisition we acquired FUMADERM and TECFIDERA 
(together, Fumapharm Products). We paid $220.0 million upon closing of the transaction and agreed to pay an 
additional $15.0 million if a Fumapharm Product was approved for MS in the U.S. or E.U. In the second quarter of 
2013 we paid this $15.0 million contingent payment as TECFIDERA was approved in the U.S. for MS by the FDA. We 
are also required to make additional contingent payments to former shareholders of Fumapharm AG or holders of 
their rights based on the attainment of certain cumulative sales levels of Fumapharm Products and the level of total 
net sales of Fumapharm Products in the prior 12-month period, as defined in the acquisition agreement. 
During 2017 we paid $1.2 billion in contingent payments as we reached the $11.0 billion, $12.0 billion, $13.0 
billion and $14.0 billion cumulative sales levels related to the Fumapharm Products in the fourth quarter of 2016 
and the first, second and third quarters of 2017, respectively, and accrued $600.0 million upon reaching $15.0 
billion and $16.0 billion in total cumulative sales of Fumapharm Products in the fourth quarter of 2017.

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BIOGEN INC. AND SUBSIDIARIES
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — (Continued)
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We will owe an additional $300.0 million contingent payment for every additional $1.0 billion in cumulative 
sales level of Fumapharm Products reached if the prior 12 months sales of the Fumapharm Products exceed $3.0 
billion, until such time as the cumulative sales level reaches $20.0 billion, at which time no further contingent 
payments shall be due. If the prior 12 months sales of Fumapharm Products are less than $3.0 billion, contingent 
payments remain payable on a decreasing tiered basis. These payments will be accounted for as an increase to 
goodwill as incurred, in accordance with the accounting standard applicable to business combinations when we 
acquired Fumapharm. Any portion of the payment which is tax deductible will be recorded as a reduction to goodwill. 
Payments are due within 60 days following the end of the quarter in which the applicable cumulative sales level has 
been reached. 
Contingent Development, Regulatory and Commercial Milestone Payments
Based on our development plans as of December 31, 2017, we could make potential future milestone 
payments to third parties of up to approximately $4.2 billion, including approximately $0.7 billion in development 
milestones, approximately $1.5 billion in regulatory milestones and approximately $2.0 billion in commercial 
milestones as part of our various collaborations, including licensing and development programs. Payments under 
these agreements generally become due and payable upon achievement of certain development, regulatory or 
commercial milestones. Because the achievement of these milestones was not considered probable as of 
December 31, 2017, such contingencies have not been recorded in our financial statements. Amounts related to 
contingent milestone payments are not considered contractual obligations as they are contingent on the successful 
achievement of certain development, regulatory approval and commercial milestones. 
Other Funding Commitments
As of December 31, 2017, we have several on-going clinical studies in various clinical trial stages. Our most 
significant clinical trial expenditures are to CROs. The contracts with CROs are generally cancellable, with notice, at 
our option. We have recorded accrued expenses of approximately $40.0 million in our consolidated balance sheet 
for expenditures incurred by CROs as of December 31, 2017. We have approximately $460.0 million in cancellable 
future commitments based on existing CRO contracts as of December 31, 2017.
Tax Related Obligations
We exclude liabilities pertaining to uncertain tax positions from our summary of contractual obligations as we 
cannot make a reliable estimate of the period of cash settlement with the respective taxing authorities. As of 
December 31, 2017, we have approximately $77.3 million of net liabilities associated with uncertain tax positions.
As of December 31, 2017, we have accrued income tax liabilities of $989.6 million under the Transition Toll 
Tax, of which $78.3 million is expected to be paid within one year. The Transition Toll Tax will be paid over an eight-
year period, starting in 2018, and will not accrue interest.
Solothurn, Switzerland Facility
In December 2015, we purchased land in Solothurn, Switzerland and are building a large-scale biologics 
manufacturing facility at this site. We expect this facility to be operational by the end of the decade. As of 
December 31, 2017, we had contractual commitments of $270.0 million for the construction of this facility.
Leases
We rent laboratory and office space and certain equipment under non-cancelable operating leases. These 
lease agreements contain various clauses for renewal at our option and, in certain cases, escalation clauses 
typically linked to rates of inflation. Rental expense, net of sublease income under these leases, which terminate at 
various dates through 2028, amounted to $65.3 million, $68.7 million and $68.6 million in 2017, 2016 and 2015, 
respectively. In addition to rent, the leases may require us to pay additional amounts for taxes, insurance, 
maintenance and other operating expenses.

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