United states securities and exchange commission

Table of Contents
81
amounts due in connection with anti-CD20 
therapeutic programs.
Net income was lower in 2017, primarily due to 
the Transition Toll Tax under the 2017 Tax Act and 
higher depreciation and amortization.
For 2016 compared to 2015, the increase in 
cash provided by operating activities was primarily 
driven by higher net income, non-cash charges for 
depreciation and amortization, a comparative increase 
in accrued expenses and other liabilities, partially 
offset by a comparative increase in accounts 
receivable.
Investing Activities
For 2017 compared to 2016, the increase in net 
cash flows used in investing activities was primarily 
due to:
• 
the
 $795.2 million payment made to Forward 
Pharma to license Forward Pharma's intellectual 
property, including Forward Pharma's intellectual 
property related to TECFIDERA;
•  an increase in purchases of property, plant and 
equipment primarily related to the construction 
of our Solothurn, Switzerland facility;
• 
$175.0 million in milestone payments made to 
Ionis and Samsung Bioepis; and
•  the $120.0 million payment made to Remedy for 
the purchase of BIIB093.
These increases were partially offset by an 
increase in net proceeds of marketable securities.  
For 2016 compared to 2015, the decrease in 
net cash flows used in investing activities was 
primarily due to a decrease in net purchases of 
marketable securities and cash paid for the 
acquisition of Convergence Pharmaceuticals 
(Convergence) in February 2015, partially offset by an 
increase in the contingent consideration related to the 
Fumapharm AG acquisition. 
Financing Activities
For 2017 compared to 2016, the increase in net 
cash flows used in financing activities was primarily 
due to an increase in cash used for share 
repurchases, the payment made for the redemption of 
our 6.875% Senior Notes due March 1, 2018 prior to 
their maturity, the $302.7 million net cash 
contribution made in connection with the spin-off of 
our hemophilia business on February 1, 2017, and 
the net distributions to noncontrolling interest, 
including the payment made to Neurimmune in 
exchange for a 15% reduction in royalty rates payable 
on products developed under the agreement, including 
on potential commercial sales of aducanumab. 
For 2016 compared to 2015, the decrease in 
net cash flows provided by financing activities was 
primarily due to the issuance of our senior unsecured 
notes issued in the third quarter of 2015, partially 
offset by a decrease in the purchases of common 
stock.
Contractual Obligations and Off-Balance Sheet Arrangements
Contractual Obligations
The following table summarizes our contractual obligations as of December 31, 2017, excluding amounts 
related to uncertain tax positions, funding commitments, contingent development, regulatory and commercial 
milestone payments, TYSABRI contingent payments and contingent consideration related to our business 
combinations, as described below.
 
Payments Due by Period
(In millions)
Total
Less than
1 Year
1 to 3
Years
3 to 5
Years
After
5 Years
Non-cancellable operating leases (1), (2)
$
428.5 $
48.3 $
92.1 $
88.3 $
199.8
Long-term debt obligations (3)
9,430.0
244.8
1,983.3
1,396.3
5,805.6
Purchase and other obligations (4)
1,657.1
637.3
344.9
234.6
440.3
Defined benefit obligation
91.8
—
—
—
91.8
Total contractual obligations
$ 11,607.4 $
930.4 $
2,420.3 $
1,719.2 $
6,537.5

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82
(1)  We lease properties and equipment for use in 
our operations. Amounts reflected within the 
table above detail future minimum rental 
commitments under non-cancelable operating 
leases as of December 31 for each of the 
periods presented. In addition to the minimum 
rental commitments, these leases may require 
us to pay additional amounts for taxes, 
insurance, maintenance and other operating 
expenses. 
(2)  Obligations are presented net of sublease 
income expected to be received for the vacated 
small-scale biologics manufacturing facility in 
Cambridge, MA, the vacated portion of our 
Weston, MA facility and other facilities 
throughout the world. 
(3)  Long-term debt obligations are primarily related 
to our Senior Notes, including principal and 
interest payments. 
(4)  Purchase and other obligations primarily includes 
our obligations to purchase direct materials, 
$989.6 million related to our current estimate of 
the impact of the 2017 Tax Act, $270.0 million 
in contractual commitments for the construction 
of our large-scale biologics manufacturing facility 
in Solothurn, Switzerland and $111.3 million 
related to the fair value of net liabilities on 
derivative contracts. 
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, Inc. (Stromedix) and Biogen 
International Neuroscience GmbH (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 our consolidated financial statements 
included in this report.
Fumapharm AG
In 2006 we acquired Fumapharm AG. As part of 
this acquisition we acquired FUMADERM and 
TECFIDERA (together, Fumapharm Products). We are 
required to make contingent payments to the 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.
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 that 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 

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