In 1976, under the Sixteenth Amendment to the United States Constitution, Congress enacted Internal Revenue Code ("I.R.C") 280A in response to the tax treatment of vacation rental income and expenses. Tax-payers were renting their personal dwellings/units less than 15 days during the taxable year while claiming enormous business expenses against little to no rental income.
I.R.C 280A contains a de minimis rule. If a taxpayer rents his/her personal unit for less than 15 days during the taxable year ("de minimis rental"), it is "illegal" for that taxpayer to claim that he/she is engaged in any hotel/motel business activity and forbidden from claiming any business expenses against any revenue. All rental income under the de minimis rule is tax exempt.
If you feel that any state or local official is trying to take away your Sixteenth Amendment right by forcing you to obtain a business license and/or conditional use permit for a business in which you are not legally engaged, and forcing you to commit tax fraud with the Internal Revenue Service, please contact an attorney.