This is a 5-year-deal is set to begin in the year 2021. Hulu currently has the domestic streaming rights to Seinfeld but their rights will expire by the year 2021.
It has not been disclosed how much Netflix paid Sony for the global streaming rights to Seinfeld. Hulu paid an estimated $160 million per year for domestic rights. So I can see Netflix paying close to $200 million per year for the global rights to Seinfeld.
Netflix needs to remain competitive with other streaming services like Disney+ and HBO Max coming in the near future.