The pop superstar and the NFL player, both 36, are due to tie the knot in New York in July but haven't told their invited guests exactly where the nuptials will occur.
"Taylor and Travis told guests to be in NYC. No other location was provided," a source told Us Weekly.
"They're putting their guests on hold for a couple days. They are spending a lot of money - in the millions."
Meanwhile, it was previously claimed that Taylor and Travis were preparing for a two-day wedding celebration at New York's Madison Square Garden.
The couple is said to be planning an intimate ceremony followed by a much larger gathering over the Fourth of July holiday weekend.
The couple has chosen Madison Square Garden as the venue for the celebrations, with an initial event attended by around 100 close family members and friends before a larger reception said to include between 1000 and 2000 guests, according to The New York Times and Page Six.
"Privacy was of number one importance to them both," a source told Page Six.
"Everyone's been sworn to secrecy," another insider said.
Invitations were reportedly issued over the phone rather than by traditional mail in an effort to reduce the risk of details being leaked.
Several of Travis' Kansas City Chiefs teammates had reservations at the Marriott Marquis in Midtown around the reported wedding date, Page Six also reported.
Speaking to Entertainment Tonight, Travis' fellow NFL tight end and Tight End University co-founder George Kittle said he remained uncertain about where the celebrations would take place.
"I actually asked Travis last night (whether it was at Madison Square Garden) and he laughed at me, so. I'm half expecting there to just be a jumbo jet on a runway and they put us on a plane somewhere," Kittle said.
The New York Post reported a permit application submitted by Winick Productions requested temporary street closures around Madison Square Garden and sought permission for a public tent to be erected outside the venue.