Brad Pitt & Angelina Jolie's Prenup is Clear

Brad Pitt and Angelina Jolie are not going to have big financial issues, because they were only married for 2 years and they might have been expecting a divorce since day 1 ... 'cause they have a prenup spelling out exactly who gets what ... TMZ has learned.

Sources close to the couple tell us their prenuptial agreement is ironclad and details the specifics of their combined fortune ... a reported $400 mil.

Brangelina have 12 total properties together ... all of which they snatched up either before they were married or before they were even dating. 7 of those belong to Brad, 2 to Angie and 3 which they bought together prior to tying the knot in 2014.

It's unclear who exactly shelled out what for those 3 properties, which include a vineyard in France, a mansion in New Orleans and an apartment in NY ... but we're told the prenup makes divvying all that up simple.

Rather than properties being an issue in the divorce, we're told CUSTODY of their kids will be where the war really plays out.

As we reported ... Brad plans to fight for joint physical custody of their 6 children.