Beleaguered writers searching for any edge they can find to keep solvent, which includes writing off expenses (for most, that's a laugh to begin with) could do worse than take a page from the playbook of British writer Dennis Wheatley. Wheatley's sort of forgotten now, but in the 1930s he was quite the ticket, selling hundreds of thousands of copies of such potboilers as Murder over Miami, or the occult thriller The Devil Rides Out (later a successful Hammer film, with Christopher Lee.)
Anyway, reviewing a biography of Wheatley ( The Devil Is a Gentleman, by Phil Baker) in The Literary Review (Dec. 2009/Jan. 2010), Andrew Lycett notes that, in 1960, Wheatley formed himself into a limited company, through which all his expenses could be funnelled. He quotes a letter Wheatley wrote - to himself:
It has occurred to the directors that no book by you has as its background the Adriatic coast of Italy and the Dalmatian coast. As there is much fascinating history in connection with this part of Europe, the directors would like you to consider making use of it and, with this intention, they suggest that you spend a few weeks in the Adriatic.
As for me, I'm already planning to set my next novel, er, make that first novel, in Tahiti. Unless one of you beats me to the punch.