K.C. Cerna can take a break from work and relax by the pool or play with her golden retriever anytime she wants. She’s her own boss. She built her 300-square-foot office in her own backyard ? literally. “You don’t have the high overheard of a storefront, and you can invest your money in your business and clients,” she said. Cerna is one of the 20.7 million people across the country who work at least partially from home, according to the Bureau of Labor Statistics. About a third of those workers are self-employed and run a home-based business. And just like millions of other Americans, Cerna plans on taking a home office deduction on her income tax this year.