Gross soc sec benefits are 55,064. Medicare premiums total 9660. That nets to 45404. Taxable amount on line 4b shows 46804. Where does the 1400 come from?

[rcanell725]

No medicare part c premiums

[Zbucklyo · Accepted solution]

Medicare premiums paid are not a direct reduction in income, but an itemized medical deduction taken on Schedule A.  They only reduce taxable income to the extent they exceed 7.5% of your AGI and you otherwise itemize.  In your case, 85% of your social security benefits are taxable, which is the $46804.