Yes I know I'm late to the conversation, but I just saw it...I'm a retired master and live FT in my RV and travel extensively. I have all my retirement in a 503b. This allows for everything used Housing Allowance is not taxable. However, Anything over my allowance must be claimed as income and will be taxed. I can't just arbitrarily say something is HA, it must fit within the allowable expenses... Wish fuel and vehicle maintenance while pulling my 5th wheel was allowed? I think that only applies if you have a class A, B, or C motorhome.