*Loan,banking and credit>>>tax bracket

Is there a site to find how much I can make on a single paycheck without going into a new tax bracket?

For example if I make $1499 gross I might pay 21% tax, but if I make a dollar more -- $1500 gross -- I might enter a new tax bracket and end up will less net pay

The US tax rates are a progressive tax - You do not move into a bracket and pay that amount on your entire earnings, you move into a bracket and pay that amount on the earnings in that bracket.

Also the person who explained that this can't be calculated based on your gross pay was "right on". I can make the same gross pay as you and pay a much lower or higher "effective rate" of taxes based on deductions, exemptions, credits, etc.

No one should ever try to make less to reduce taxes. IF you have the option though it makes good sense to negotiate compensation packages that have less taxable income and more "non taxable" benefits.

taxes are based on year not check to check.
It doesn't work that way. Only the additional dollar you earn, in your example, would be in the higher tax bracket. You wouldn't take home less money.
It's based on your annual salary.
The easiest way to check is to go to www.irs.gov they can usually give you an idea of your yearly wages and what tax bracket you are in.
It's your taxable income, not your total income, that puts you into a particular tax bracket. To calculate taxable income, everyone has items to subtract from their total pay - exemptions, standard or itemized deductions, and possibly several adjustments.

But once you get your taxable income calculated, yes, you can see what bracket you're in. One place to look is to download the 1040 instructions from irs.gov - the schedules are on page 82. The bracket depends on your filing status as well as your taxable income.

These tables explain how the brackets work. For whatever bracket you're in, you only pay that percent on the number of dollars of taxable income you have that are over the top limit of the next lower bracket. So it would not happen that because you made extra money putting you into a higher bracket, you'd end up with less net pay, since only the amount that put you in the higher bracket would be taxed at the higher rate.