As was already pointed out, you want to lower your withholding u2022 not your refund (which will increase your refund, or reduce your tax due).Anyway . . . itu2019s not a good thing to do, for several reasons. 1. Employers are no longer automatically required to submit W-4u2019s with more than 10 allowances to the IRS, but (i) that could change at any time, and (ii) a particular employer can be directed to submit W-4u2019s, or certain W-4u2019s whenever the IRS wants.2. You will likely be under-withheld u2022 by how much depends on your circumstances u2022 and that could result in underwitholding penalties at tax time.3. The W-4 is a tax form that you are signing under penalty of perjury, saying that the information is correct (read the signature line). Part of that information is that you are entitled to X allowances per the worksheet (based on dependents, deductions, etc.). Nobody expects those number to be absolutely precise, but when youu2019re entitled to 7 allowances, and you claim 17, thatu2019s hard to write off to an error in estimates.4. Finally, you say you are in Los Angeles. I donu2019t know what California does in terms of withholding allowances, but if u2022 like many other states u2022 it uses your Federal W-4, then youu2019re just compounding your problem.As far as it being u201clegalu201d, I canu2019t see you going to jail over it, but if someone wanted to make something of it, willfully providing false information on a W-4 is a crime, punishable by up to $1000 fine and 1 year in jail. (Itu2019s a form of tax evasion, but it is its own violation.) Perjury is also a separate crime (remember the signature line), punishable by a fine of up to $250,000 and 3 years in prison. So, to answer your specific question, no, itu2019s not u201clegal.u201d