If you're still working on your income tax return, don't despair. You still have 14 hours to finish them and file them electronically. 14 Whole Hours! You could polish off a chapter or two with that time...tomorrow.
But if you're a writer, proceed with caution. The rules for reporting earnings from your work can be tricky, and unlike a novel or short story, you can't just make this stuff up. After all, writing is a business.
"I don't have readers, I have customers.", Mickey Spillane once said. He was right. And I hope you had LOTS of customers in 2013. And as few taxes due as possible.
Start with the IRS publication guide for Schedule C, small business, IRS PUB 334.
Got a home office? It may be deductible. Check IRS PUB 535 to review allowable business expenses, including how to write off a home office. These rules are very specific.
How do you know what records & receipts to keep? Check IRS PUB 552 to see what sort of book-keeping you need to do.
These links are in the form of pdf files, and they're easy to search for key phrases like "home office", "travel expenses", and "Help!" (this last one's not in there...trust me, I checked).
You might want to start with a checklist. Riley & Associates has a great one for expenses, geared towards writers, on their website here.
Did you go to Sleuthfest, Bouchercon, Love Is Murder? Travel and hotel expenses may be deductible if your purpose was for education, promoting your writing and pitching agents & editors, and not just to meet your favorite author.
Even meals are deductible if you talked business. Did you discuss your book? Of course you did! But beware...meals are only 50 % deductible, so keep all your receipts.
Don't forget to deduct membership dues to writing organizations like Sisters In Crime and Mystery Writers of America. You can even write off that subscription to Writer's Digest.
And when all is said and done, wipe the blood from your brow and get back to work. And take a deep breath...taxes only come once a year. But you still need to finish that first draft.