Instead, she's going to stay home and mark the milestone with a holiday party.
"I definitely want a winter-themed birthday – Christmas-themed," she tells PEOPLE. "And I'd really like to have it in my condo. I think that would be wonderful."
Though Swift says she's "not, by nature, a party girl," turning 21 will help her social life.
"It'll be cool that I'll be able to go to a lot of concerts that my friends always go to and I sit at home because it's 21 and over," she says. "Other than that, I don't think I'm going to all of a sudden start being in love with the idea of going to a club."
But that doesn't mean she doesn't like to have a good time. "I like to dance around and have fun with my friends and we have a blast, but I've never felt really compelled to be drunk and I don't think that's terribly awful," she says, but "I'm not one of those people who's never going to have a drink."
While Swift was open about her party theme and drinking legally, there is no word on whether new beau Jake Gyllenhaal will be on hand to help her celebrate with a cocktail or two.