EXCLUSIVE

Jeff and MacKenzie Bezos did NOT have a prenuptial agreement so, by all rights, they will split their incredible fortune right down the middle ... sources with direct knowledge tell TMZ.

The couple will file divorce docs in Washington, where community property rules ... translation -- all earnings and income during the marriage are split 50/50.

When the couple married in 1993 -- 6 months after meeting -- Jeff wasn't even a millionaire. He didn't become one until 1997, so dreams of being the richest man in the world were pie in the sky.

The division of assets will be incredibly complicated. Aside from cold hard cash, the former couple is hardcore baronial -- they own 400,000 acres of property, making them 2 of the biggest landholders in the country. Valuing that land is complicated.

As we reported, Bezos is in a relationship with former "So You Think You Can Dance" host Lauren Sanchez, who's estranged from talent mogul Patrick Whitesell. Our sources say Lauren and Jeff started hooking up in the latter half of 2018, after they separated from their respective spouses. Lauren and Patrick are also in the middle of divorcing.

We're also told both Patrick and MacKenzie have known about Jeff and Lauren's relationship. It's still awkward -- Lauren and Patrick were super close to Jeff and MacKenzie for a decade.