How much money does one have to earn per year before they have to file income taxes

The combination of your personal exemption ($3,300) and your standard deduction ($5,150) for a total of $8,450.

So if you make $8,450 or less, you have no requirement to file an income tax return.

However, you may want to file a tax return to get withheld taxes back or to qualify for the Earned Income Credit of, if you have children, the Child Tax Credit.