Could it be for state? Federal and State are completely separate. At the end Turbo Tax shows you the NET combined federal and state. But that is just for your own info. You will get a refund and need to pay the full tax due. You can't have a tax due deducted from the other refund.
Where does it say you owe $900? Did you file your return? Did you get a letter from the IRS that they changed your return? Do you get Social Security? Was 1040 line 6b zero? A common reason could be the Foreign question. Go back through the Social Security questions. Right after you enter the SSA-1099 is a screen asking if you lived in a foreign place. People have been answering it wrong or skipping it. Answer should be No. And it is for each spouse if filing Joint. If the IRS adjusted your return for missing the taxable Social Security you do not need to amend for that.
That's why it's a good reason before you file to check your return line by line with last year and you might have seen that the taxable Social Security on line 6b was missing if it was taxable before. Then you could have questioned it.
