Justin and Hailey actually tied the knot last month in NYC -- the same day they got their marriage license at the courthouse. They had a preacher on hand -- Jeffrey Quinn, a member of the faculty at Nyack College near the courthouse.

The witness was Josh Mehl, a friend of Justin's who attends Churchome in Los Angeles.

Fact is ... People mag got it right.

As we reported, Justin and Hailey both reached out to lawyers for a prenup, but now the plot thickens. We're told they reached out the very same day they got hitched, but there was no way to get a prenup drafted and signed that quickly.

So, Justin and Hailey got married without a prenup and there's been no movement to have one drafted now. It's called a postnup -- same as a prenup but signed after the marriage.

One source said Justin is so in love he doesn't see the need for one. How's this for a need -- Justin's net worth is estimated at $250 million and Hailey is reportedly worth a couple of mil.

We're told they still plan to have a formal ceremony, but it would be a ceremony in name only because they are already husband and wife.