Offer your thoughts or opinion on the input financial query or topic using your financial background.

Why do Americans have to file taxes, even if their only source of income is from a regular job?
One significant reason it makes sense for filing to be the default is home ownership rates.  I think far more so than investment income, Americans own homes: as there is a significant mortgage interest deduction, between that and investments a large number of Americans would have to file (about a third of Americans get the mortgage interest tax deduction, and a large chunk of the richest don't qualify but would have to file for investments anyway). We also have a very complicated tax code, with nearly everyone getting some kind of deduction.  Earned Income Tax Credit for the working poor (folks making, say, $30k for a family of 4 with a full-time job get several thousand dollars in refundable credits, for example), the Student Loan interest deduction, the above mortgage deduction, almost everyone gets something. Finally, your employer may not know about your family situation.  As we have tax credits and deductions for families based on number of children, for example, it's possible your employer doesn't know about those (if you don't get health insurance on their behalf, they may well not know).  Start reporting things like that separately... and you end up with about as much work as filing is now.