Business expenses claimed on SCH C have absolutely nothing what-so-ever to do with your standard deduction on SCH A or your itemized deductions on SCH A. SCH C expenses are deducted from SCH C income and never touches the SCH A. Your SCH C expenses will not only reduce the amount of ordinay tax you will pay on that SCH C income, it will also reduce the amount of the additional 15.3% self-employment tax you pay on that SCH C income.
