What really is the tax rate on currency exchange?

WHAT REALLY IS THE TAX RATE ON CURRENCY EXCHANGE?

Ignorance is no excuse, or that's what I'm sure some will be told even after they paid what was supposed to be the proper amount of taxation...as you can call 10 CPA's, 10 IRS Agents and 10 Tax Attorney's, and I'm sure that all of them will give you at least somewhat of a different answer as per what taxes will or won't be...IMO...get a Tax Attorney, CPA, Etc...to give you a "Pre-Determined Tax Ruling", as per what your taxes will be before any Cash-In is even done...(This is obtained in writing from the IRS)...that way there's most likely no come-back on you later on...which sometimes can be very devestating and costly in most instances...Especially since it may be a large enough amount of money coming one's way, that it might not matter in comparison to what you could lose later on....but this should be something to consider?...Any other's thought's?....