Entering your income is easy enough if you're a salaried employee with a W2 form. The time consuming part is searching for and entering deductions. The tax code is ridiculously complex and there are forms for all sorts of deductions.
Even if you're pulling in 100% of your income through a W-2 job and you're sure you're not itemizing, you have to consider excluded income, above-the-line deductions, and refundable and non-refundable credits. Oh, and do you live alone or might you claim a dependent,[1] and on and on and on. People spend their whole lives on this stuff and still don't understand the half of it.
