Justin Timberlake and Jessica Biel: tying the knot ... maybe. (Joel Ryan/AP; Evan Agostini /AP)

Justin Timberlake and Jessica Biel — who split up last March, then got back together over the summer and attended the “In Time” premiere in October — are reportedly engaged, assuming a new story in Us magazine is accurate.

Us cites several unnamed “insiders” who provided confirmation that Timberlake, a.k.a. the singer and actor who might play Elton John, proposed to Biel in late December while they were vacationing in Jackson, Wyo. So far, reps have not commented; I sent an e-mail to Biel’s publicist seeking confirmation but have not yet received a response.

Rumors of a marriage proposal began to circulate just before Christmas — and, coincidentally, shortly after Britney Spears, Timberlake’s ex, announced her plans to marry Jason Trawick — when a Jackson jewelry store posted to its Facebook page about the pair getting engaged at a nearby resort. That post has since been removed.

As GossipCop noted, the story was shot down at the time. Us’s article does not specify when the proposal took place beyond that “late December” time frame.

Even when the two were in their off-again phase, Timberlake spoke highly of her. Earlier this year in Vanity Fair, he called Biel “the most significant person in my life.”

The two first started dating in 2007.

We will update this post once a more official confirmation — or a denial — is issued.