Many people start out doing their tax returns, and then find that their financial life gets more complicated. Simple individual tax returns are straight-forward, you add up your W-2s, add any 1099s, and then look at deductions. With the standard deduction growing to $12,550/person and $25,100/couple for 2021, most middle income individuals will just take the standard deduction, even with a large mortgage. Higher income individuals may still benefit from itemizing, particularly if they max out their $10,000 (State and Local Tax) deduction plug a mortgage. Even moderate amounts of business income with write-offs can easily be done on Schedule C.