Twitch Prime members can claim up to 12 months of Nintendo Switch Online for free. Nintendo Switch Online benefits include online play for the Switch, cloud saves, and access to classic NES games with new games added each month. The annual subscription normally retails for $19.99.
The good news for existing Nintendo Switch Online subscribers is that they can still receive the offer too. The months will just be stacked on top of your existing subscription, extending the expiration date up to a year.
Take note that you have to first claim three free months of Switch Online through Twitch Prime. The offer starts today and expires on September 24, 2019. After 60 days, you can go back to Twitch Prime to claim another nine months for free. The free nine-month offer has to be redeemed by at least January 22, 2020.
Once you are signed up for Twitch Prime, click here to visit the Twitch Prime page where you can claim your free Nintendo Switch Online subscription.