Since the tax reforms under Trump, the standard deduction is high enough that there's not much point in anyone else doing my taxes. Prior to that, though, the

Since the tax reforms under Trump, the standard deduction is high enough that there's not much point in anyone else doing my taxes. Prior to that, though, the tax code is so encumbered with all of the various exemptions and deductions and carve outs that it was easier and less stressful to have someone else do it. I somewhat recently bought a house, so the mortgage interest deduction comes close on its own to not take the old standard deduction. There are plenty of these things that the government isn't going to know about- health expenses, state and local taxes (state would be easy enough to keep up with, but local taxes change all the time), even things like a deduction if you keep a home office. The operating theory is that the federal government isn't incentivized to hunt down all of these things for you (or cannot legally know about ahead of time without violating your privacy), and will over-charge you by pre-filling out the paperwork. This is where commercial companies believe (or claim) that they are doing good- they ostensibly have a motivation to provide better results than their competitors, and so will do the best job to ensure you are paying the legally required amount of taxes without overpaying.