Why do I owe money?

[gbelyaye]

I got mail from the IRS about Recovery Rebate Credit. I realized that I DID receive the stimulus payment when I believed that I did not. Why do I owe nack over $900 of their $1400 payment?

[MinhT1]

The IRS has reduced your original refund claimed on your tax return by $1,400.

If you had a refund of $500, then you now owe $900.