If you have no permanent address and you want to file a US federal income tax return, you will need to include a "c/o" address where you receive mail (whether that is a PO Box or the address of a relative) on your tax return.
Also if you do not have any taxable income for the year or less than $400 of self-employment income, then you are not required to file either a US federal or state income tax return for that year.
