Have the itemized deductions reduced your taxable income to zero? If so, entering more itemized deductions will have no further affect on the tax refund since there would be no tax liability.
To review your Form 1040 using the online editions, click on My Account at the top of the program screen. Click on Tools. Click on View Tax Summary. Click on Preview my 1040. Scroll down to Line 43. Is your taxable income zero?
