- Travel. Anytime you traveled for research purposes, to and from a conference or book signing, all of those expenses can be deducted. The cab ride to the airport, the airfare or the miles driven on your car, all should be reported to your accountant. (There are different rules for different deductions so I'd let the expert sort that out.)
- Home Office. Most writers work from home and therefore have a slew of things to deduct. If you have an office that you use exclusively for writing (or are at least able to prove that you do) you can deduct a portion of your rent or mortgage. If you purchased a new computer, printer, or fax that you'll use exclusively for writing, you can deduct that as well. In addition to the obvious office supplies and postage stamps, you can also deduct a portion of your electric and gas bill. If you're working from home, all of the things you use to keep your office going can be deducted as business expenses.
- Entertaining. Though you cannot deduct entire bar bills and dinner checks, it is possible to deduct portions of your entertaining expenses. If you take another writer out for drinks, treat an agent to dinner or take them to a ball game, all of that should be reported to your accountant. Little tip, next time you're at a conference, each member of your entourage should offer to get a round. That way, instead of each person only paying for themselves, they are paying to entertain colleagues and can therefore deduct it for tax purposes.
- Research. This one can get a bit tricky and I believe deciding what to and not to deduct as research expenses is a matter of risk taking. If you're writing a book set in Japan, by all means, go to Japan and deduct the trip, hotel stay and various restaurant and bar bills as research. If your protagonist is a bartender and you deduct every bar bill, every weekend, as research purposes, that's a bit more risky. When doing research for a novel or article, make sure that everything you spend is a necessary expense and that it is directly related to what you're writing about.
*Note for the newbies. Just because you didn't earn a lot as a writer this past year, doesn't mean you are not a writer and cannot deduct these expenses. The general rule of thumb is that you should make a profit within 5 years. And even then, you only run the risk of being audited, and if you do get audited, you only need to convince the IRS that you are in business to make a profit. Come on, we're writers. We can convince the pope that Jesus was just a hippie. If you are serious about writing, you will eventually make a profit, probably well within the 5-year expectation, but until then, don't be afraid to deduct.