They said I would have to prove that I have 10 exemption
No....they are confused.....if you claim more than 10 then they are required to forward the W-4 to the IRS to let them evaluate if any changes need to be made. See enclosed Q&A which is directly on point as your question.
My answer is not intended to be giving legal advice and this topic can be a complex area where the advice of a licensed attorney in your State should be obtained.
1 found this helpful
2 lawyers agree
I agree with Mr. Corrigan, but please do the calculations to make sure that you are entitled to claim 10 exemptions, it may not be worthwhile to get less withheld now if you will owe tax and underpayment penalties when you file your tax return
3 lawyers agree