"That's what I'm trying to do," he said. "Every day, someone brings up a new area we did not think about that has to be checked, and hopefully there is a patch."

U.S. companies in areas affected by the time change will also have to modify systems to deal with companies in U.S. territories that won't change to DST, including Hawaii, American Samoa, Guam, Puerto Rico, the U.S. Virgin Islands and much of Arizona. The change could also mean complications for multinational businesses because different timeframes for DST are used worldwide.

Although the new DST schedule begins this year, the law includes provisions that could allow it to be rolled back to the old schedule, meaning that whatever changes are made this year must be reversible.

Another IT administrator, Rob Schwartz, manager of technical support at Reading, Pa.-based Boscov's Department Store LLC, said that he began DST remediation work about four weeks ago with about six staff members looking at the issue from every angle. With an assortment of IBM AIX, Microsoft Windows and Linux servers, and virtual servers in use, Schwartz estimated that at least 600 hours will be dedicated to completing the DST work at Boscov's.

"It could easily take more than that," he said. "It's not trivial, there's no question about that, so we have to look at every system."