Unfortunately, the free Hulu subscription is only available on the Spotify Premium Student plan. This is a slightly more complicated process, because after billing is canceled, users need to wait for their Showtime plan to expire (they can continue watching during this period) and then activate the free plan through their Spotify services page.
For Showtime, the process is a bit different because the current plan needs to be canceled and then reactivated. Additionally, existing Hulu users will need to be on the ad-supported plan ($6.99 per month), not have any add-ons like Showtime or HBO, and be paying for Hulu directly and not via a third-party platform like Roku or Amazon to switch their billing to Spotify. Existing Hulu users need to agree to switch their billing over to Spotify while signing up for a Student plan. Spotify notes that users can activate these free subscriptions on existing Hulu/Showtime accounts or create new ones. Once a Spotify Premium Student subscription has been purchased, users can immediately activate the free Hulu or Showtime plans to start streaming their favorite shows.
Related: Favorite Music Guru For Spotify: How To Find Your Top Artists & Tracks
