Self employment tax hurts bad. Basically this is Medicare and social security. Can be a huge amount owed seperate and in addition to income taxes. Does it ever

Self employment tax hurts bad. Basically this is Medicare and social security. Can be a huge amount owed seperate and in addition to income taxes. Does it ever! I owe over $100K in back taxes, and the majority of it is SE tax. Income tax accounts for a relatively modest portion. Self-employment tax is assessed against gross personal income (aka net business income off Sch C, in my case) prior to any personal Sch A deductions. In my case, the latter proved to be quite significant, especially since I was paying a lot of interest on a mortgage for much of the period in question. So, I had years where my taxable income for SE tax purposes was (just making up numbers here), say, $50K, while my net income for federal income tax purposes was something like $19K.