How much if I let them take out as much as possible for taxes? How much do I really make per hour?

Though I dont understand how much it would take out of your salary either way, it depends on what country and state you live, since each country has its own laws and all.

Depends on the state/country.

This. Also, if you are self employed/ employed and what write offs you are allowed too. Way too many factors.

USA, not self employed, Wisconsin

The amount taken out should be somewhere on your paystub or accessible to you somehow. Subtract that from your total pay then divide that by your hours.

You need to know how many hours you work
https://salaryaftertax.com/us
Of course that's quite simplified. Plus you'll pay tax again when you spend it.

It also depends on how you claim marital status and dependents. That does not have to match when you file for taxes. IE: You can claim 0 dependents and really have 5, then you will get a nice check from the government when you file, or you can claim 9 and have less withheld, but you will owe a lot ...

Plus it depends if any is withheld for other reasons, such as medical insurance.

If I had to guess, it will be about $5/hour taken out of the $15 (leaving about $10/hour), but it depends on so many factors... IE: If part time will be less taken out than if full time.

Soc Sec and Medi is 7,62%. Have to pay it. The new tax bracket% for single 31K is 10%, [FT 40 hours@ $15/hr]so about 60 a week withheld. About $3120 all year. At tax time in 2019, you'll take 12k off your 31k and owe tax on the 19k adjusted earnings. 10% is $1900, so you'll get a $1220 refund. Rather have that $1220 during the year? Claim Single 2 and they will take out about 60 less per week and you'll nearly break even at tax file time. WI tax rate is the same as SS/FICA, 7.65%.  To figure your actual per hour bring home, divide your take home pay by your hours worked number.

At my job, I can dictate how much "they take out". Anywhere from absolutely nothing (which means I'll have to pay the IRS) to having them deduct so much that the IRS owes me and I get a return.

The ideal situation is that, when you file your taxes, you don't owe them and they don't owe you. There's a lot of factors, though. How much you make annually, what your expenses are, if you're married, if you needed government assistance, if you have kids, if you've bought a home, if you're in school, etc. I'm not equipped to give advice on that. If you want a good penis joke or you're stuck in Xenoblade Chronicles 2, I'm your man.