There's a BIG wedding scheduled Saturday a block from Taylor Swift's Rhode Island mansion ... the question, is it for Taylor's big day?

Sources with direct knowledge tell TMZ ... a wedding will go down at Ocean House -- a ritzy hotel just a stone's throw from Taylor's digs.

Check out the enormous tent that's being constructed on the hotel lawn.

We know a permit was issued for the tent. According to the permit, there will be 220 guests. It was issued to "D & G Wedding" ... so whoever took the permit out didn't want to reveal their identity.

It gets more interesting ... there's a permit for a fireworks show. TMZ broke the story ... Taylor and Travis were set to have a wedding-related event at Ocean House on June 13th, and the same fireworks company Taylor and Travis booked for the 13th is handling Saturday's wedding.

As we reported, Taylor and Travis canceled the June 13th event last month. The question ... did they just move the date a week later to this Saturday?

TMZ also broke the story ... there has been significant activity at Taylor's mansion in the last few days. Her best friend Abigail, along with other women, were seen at the house, along with a phalanx of armed security.

From everything we're hearing ... the July 3rd Taylor-Travis event at Madison Square Garden will be a celebration for a much larger crowd and not the wedding itself.