Jay-Z is staking legal claim to the master recordings of his iconic debut album ... and it's a "buyer beware" notice, of sorts, to anyone getting ready to drop more than $1 million to buy Damon Dash's share of Roc-A-Fella Records.

TMZ Hip Hop has learned Jay's attorneys just made a legal filing that might normally fly under the radar, but here's why it's suddenly very relevant. As we first reported, Dame's third of Roc-A-Fella is going up for auction later this month, and the label's only real asset is Jay-Z's 1996 album, "Reasonable Doubt."

While Roc-A-Fella currently holds the copyright on the record and all its tracks ... Jay's attorneys have now filed notice that those rights will revert to one Shawn Carter/"Jay-Z" in 2031.

Even though Jay and Dame ain't exactly vibing these days, this legal move isn't about revenge, it's just biz -- the rights would have gone back to Jay 35 years after the record was released, anyway. His lawyers have just filed the paperwork to make it official.