Medical expenses can start to be deducted after they have reached 7.5% of your AGI....this assumes that you already itemize your taxes and do not just take the standard deduction. See link below: http://blog.turbotax.intuit.com/2013/03/04/what-are-tax-deductible-medical-expenses/
Read this thread post # 13: cpap deduction The home generator is tax deductible and some states have an additional deduction on top of the federal deduction for the home generator. Seems that the c-pap machine is not tax deductible, but the supplies and generator are. I'd ask a tax preparer though or whoever does your taxes for you.
I also have a cpap and my tax guy told me to write it off as a bussiness expense since it was required to use for my job
You can write off anything that is legally required or mandated you do, to perform your job and keep the required licenses and medical clearances that the job REQUIRES ... as far as I'm concerned. If a DOT authorized/required doctor says you MUST use a CPAP [or not work] tells me the device is a necessary job expense, especially if you would not otherwise use one. If you would use one while not on the truck, then I guess that's a decision for you to make, depending on how much you despise or don't despise paying income taxes. I don't care what that post #13 says, DOT rules are much different today then they were many years ago and if the IRS still says you can't deduct them when an official tells you you have to buy and use one, then screw the IRS. That's my 2 cents
I don't care what Post #13 has either, I'm not the one looking for a job. I recommended he ask his tax preparer and that's what I still recommend.