The fact that they have police officers, courts, and prisons (and, ultimately, an army) to enforce that power. Welcome to the real world.
In the United States specifically, the power derives from Article I, Section 8, of the US Constitution: "The Congress shall have power to lay and collect taxes [and a whole bunch of other stuff that isn't relevant here]."
amendment 16
Income Tax
income tax
Power of the Federal Government
The 16th Amendment to the U. S. Constitution allows for an income tax. Abraham Lincoln had used an income tax to finance the Civil War but it was latter found to be unconstitutional thus necessitating the 16th Amendment.
the 16th amendment...
Amendment 16
1. the employer withholds estimated taxes 2. the taxpayer files a tax return the government receives a tax payment or gives a tax refund 3. the government receives a tax payment or gives a tax refund
The power to engage in war. The power to levy income tax.
The Internal Revenue Service a.k.a. the government of the US
Power of the Federal Government
Income tax an amount of tax that is due on your TAXABLE INCOME amount for the tax year.