OP dont be fooled with that common belief that OT money is taxed differently for some magical reason. I worked 2 years in the Tax preparation industry and have never see a case were working OT made you a candidate for a secret special tax.
Tax rates are a very straightforward mathematical function. Is based on how much you made combined at the end of the tax year, minus deductions, credits, etc. Then your income is split in brackets or sections and certain % amounts of each bracket is taxed. Never will you be double taxed in any of your earned dollars...( some cases of double taxation exist, but this happens mostly to corporations or business) What this means is that if you would make lets say 40k that year you would be taxed appropriately based on that income, any OT that you did that year will just increase your earnings from lets say 40k to 50k total at the end of the year, and will be taxed based in a gross income of 50k.
Never will working OT have a negative return on your earnings, you will always make a lot of money after tax when working OT.