Nearly one in three small small businesses say underestimating monthly expenses was the biggest mistake they made when starting up.

The survey of 500 small businesses was done by specialist insurer Hiscox USA, which found that 32 percent of small businesses thought monthly expenses would be less than they were.

The next three biggest mistakes were hiring the wrong people (20 percent), not knowing how to market and sell the product (18 percent) and not securing enough financing up front (18 percent).

“People who take the leap often have great energy and passion for their area of expertise,” said Kevin Kerridge, Hiscox small business insurance expert, in a press release. “They have a clear goal, but as they embark on their journey they may not foresee the bumps along the highway. Cash flow, human resources, marketing and insurance issues can seem boring but are hugely important.”

The survey also found that 33 percent of business owners showed a lack of understanding about the impact of taxes, followed closely by financing and credit (26 percent) and hiring and firing (24 percent).