The IRS (and its rules) are more a friend here than you might imagine.  They’ve actually made it easy for you.  You get a W-2 for you salary from your full-time job.  You should get a 1099-MISC from your freelance clients – be sure you include the income even if you don’t!  Your tax return is filed on a Form 1040 and you take the standard deduction.  So far, I’m not telling you anything new.  Here’s the new part:  your business expenses have nothing to do with the form so far; they go on another part of your return.  You can continue to take the standard deduction and you can deduct all those expensive software & hardware purchase as freelance business expenses.