To be considered for a Grammy nomination, an artist must release their song, record, or album during the "product eligibility period," which usually runs from Oct. 1 through Sept. 30 of the following year.
So, for example: "Shake It Off" arrived on Aug. 18, 2014, and earned Record of the Year, Song of the Year, and Best Pop Solo Performance Grammy nominations in 2015. Its album 1989 was released on Oct. 27, 2014, and yielded three Grammy wins — including Album of the Year — in 2016.
So Swift's Reputation album won't qualify for the next Grammy Awards, but she might try to rack up some album nominations for 2019. As for that single she's dropping tomorrow night? That will qualify for the 2018 Grammys.