Where Can I Find What "Other Taxes" I am being charged?

[pcpatter]

I am looking at my tax summary under the tax tools. On the line that says "Other taxes" there is an amount listed which is adding to the taxes I owe (and thereby reducing my refund). However, I cannot locate where this amount is coming from and it is a substantial amount. Any help would be appreciated! I do have self-employment income so perhaps it is from this? 

[MinhT1]

Other taxes come from line 21 of Schedule 2 (Form 1040) and can be the sum of a variety of taxes such as self-employment tax, alernative minimum tax (AMT), repayment of excess advance premium tax credit,...

Please see Schedule 2 for a full list of possible additional taxes.