Sorry to pop your bubble, but... I live in Denmark, and all of the above use cases are automatically calculated by our tax auth.. My most complex tax-filing w

Sorry to pop your bubble, but... I live in Denmark, and all of the above use cases are automatically calculated by our tax auth.. My most complex tax-filing was: - Full-time job - Extra "non-job" salary (board membership) - Investment income from two different providers - Expenses for multiple bank loans and mortage, and external credit card companies - Three different companies (LLCs) that I own All of that info send to the IRS (by law) from all provider. My time for tax-filing 10 minutes to look it through (and do nothing as it was correct). This year I had 1 change to the taxes. The interest from a small collective loan for our home-owners association was not automatically filed, and I had to enter that by hand... Took 5 minutes.. Small note, my three companies also had my time spent doing tax stuff, but that is by law required of the LLCs and the companies have a (shared) accoutant doing that.. Other note. Even royalties (for books, music etc) are correctly calculated by the danish IRS due to the requirements of posting from the companies doing payouts.. tl;dr: The requirements of the payer and all financial institutes to file to the IRS is extremely effective...