Jack Osbourne felt something was amiss while poring over his credit card statements … and he was proven right when he discovered he’d been the target of identity theft. Law enforcement sources tell TMZ … the red flags started flying for Jack when he saw just a few odd charges, and it prompted him to start looking back at previous months’ statements. Good thing he did, ’cause lo and behold … he found a slew of charges he never made.

We’re told Jack contacted law enforcement and reported the unauthorized charges totaled around $30k. It appears the charge to his card came from an employee of a monthly service Jack has scheduled at his house. The LAPD is now investigating the case, though no arrests have been made. We know getting hit for five figures worth o’ cash flat-out sucks … but it beats the last time Jack fell victim to a crime.

TMZ broke the story … Ozzy and Sharon’s son was brutally attacked back in April after an apparent homeless man walked up to him on a coffee shop patio and sucker punched him. The attacker was tracked down and arrested for battery and assault. We’ll see if Jack has justice on his side again with the credit card scammer.