Early withdrawl of $7143,56 from a Roth IRA before I turned 59 1/2. What happened to the $1200 that was withheld by the custodian? Why do I owe $714 additional taxes?

I understand there was a 10% penalty ($714), but the $1200 should have included $486 in withheld taxes after that penalty.  Is that sent to the IRS, or do I have to recover that from the custodian?