It is not automatic, that is, it takes effort to answer all the questions and enter the correct data. However, the process is systematic and complete, so it is pretty darn good! The process is staged by income and expense types, additions and deductions. There is help available when the IRS instructions get confusing. The calculation of taxes gets more complex each year and the H&R Block tax package keeps up and assists in making the best choices.
This software greatly simplifies filing of your taxes. It is a necessity if you do your own taxes. And the algorithm is probably more accurate than a trained and experienced person.