Are you sure they are tax free ?    If they are then they should not be on box 1 of the W-2 ... a corrected form should be issued ...   https://www.irs.gov/individuals/international-taxpayers/allowances-differentials-and-other-special-p....

Please explain what you mean by a living allowance  and why you think it should not be taxed.  There are several possibilities and we can’t really provide answers without more details.