Charities tied to Mets-owning brothers-in-law Fred Wilpon and Saul Katz got hosed for $8 million in the Bernie Madoff scandal, new tax records show.

The losses came after the nonprofits posted several years of eye-popping returns on their investments with Madoff — as much as 65 percent in Wilpon’s case, according to the filings — before the Ponzi scammer’s financial house of cards collapsed and the gains were revealed to be phony.

The Mets Charity Foundation — which counts Katz, Wilpon and his son, Mets COO Jeff Wilpon, as trustees — took the biggest hit, losing $3.8 million in the investment scheme, its IRS filing shows.

The loss left the $4.8 million foundation with “an inadequate amount of financial resources on hand” to “immediately satisfy” $752,000 in payouts to some of its causes, including $80,000 earmarked for Dominican Republic hurricane relief and $6,900 for the James Plummer scholarship, according to the paperwork.