Thanks for your question.
Line 65 of the 2008 Form 1040 is Additional Child Tax Credit. Be sure to check the Form 8812 you completed when you filed the return. If Turbotax actually made a computation error, you should contact Intuit immediately and seek re-imbursement (of at least the interest amount) due to a programming error. Go to https://turbotax.intuit.com/support/contact/index.jsp
If you find out that the error was actually due to a mistake you made typing in the data, then you will have to pay the amount that is due or call the phone number on the IRS notice and ask to set up an installment plan if you cannot pay the full amount immediately.
Hope this helps,
Sorry, I was looking at the 2009 form instead of 2008. You are right.
First you should check to make sure that you entered all the data from your Form W-2's into Turbotax correctly, making sure the amounts for social security wages and social security taxes were entered correctly. Also, if you are married, be sure that you entered the correct spouse for each W-2. If they were entered correctly, you should contact Turbotax as explained above and notify them of a programming error.
This credit is for those who worked at 2 or more jobs and had too much social security tax withheld from their wages because when the jobs are combined, your wages exceed the social security wage limit of $102,000. The amount of credit should equal all your social security taxes combined from all your W-2s minus $6,324. You cannot combine your spouse's wages to meet this limit as it applied to each of you separately.
If one of your employers made a mistake and withheld too much social security tax, you will need to ask for a correction and seek reimbursement from your employer. Your social security wages multiplied by 6.2% should equal your social security taxes. If it doesn't this means your employer made a computation error.
Hope this helps,