It's for anyone entering the national parks, and for all types of entrance passes (day or annual, single or group, etc), so come celebrate with us.
Note that this is for entrance
fees only, not campground fees. So if you stay in a national park you'll save the entrance portion, but still pay for your site; if you just visit for the day to see the sights, no fee. Also, this for the federally run national parks; many parks are provincially owned and operated and so not part of the promotion.
To make this simple for annual passes, passes purchased during 2016 will expire on the corresponding month in 2018 (24 months after purchase), instead of in 2017 (the usual 12 months after purchase).
Parks Canada - Plan your visit - 2017 free admission