Ask small-business owners how much time they spend on the job and the answer is usually the same: all of it.

Yet, some entrepreneurs manage to launch a start-up on the side without quitting their day job. While it’s a lot like leading a double life, many say the rewards are worth it — namely, extra income and the chance to test out a new, often more enticing career without losing steady paychecks and benefits.

“Starting a business on a part-time basis is one of the most efficient ways of finding out if a business will work for you,” says Paul Edwards, co-author of 16 books on self-employment, including “Finding Your Perfect Work.”

In 2004, Mr. Stim decided to start a side business, an audio-book production business. It was part of his research for “Whoops! I’m in Business,” a guide he wrote on turning a passion or hobby into a business.

The new studio landed a contract almost immediately, and “boy, you really freak out once you’ve got a contract,” he says. One concern: “How do you not blow it at both jobs at once?”

Mr. Stim says he’s able to swing both by working for Nolo from home, which saves valuable commuting time, and by enlisting his wife as a partner at the sideline business, Sutro Studios.

One tax benefit to the side business: He can write off the cost of audio equipment, which he enjoys as a long-time music-production enthusiast. If the side business is something you love, there’s nothing like it, Mr. Stim says. “It augments my income, and it gives me something fun to do.”

Because of the drain on your free time, be sure to involve family members in the decision-making process. Without the proper amount of family consent, this can torpedo the relationship with the family.

startupjournal.com