Thanks to a recent change in IRS regulations, it's more important than ever that businesses pay their payroll taxes in a timely and accurate fashion. As of March 31, 1991, any company that accumulates $100,000 or more of combined FICA and federal-income-tax withholdings during any pay period will be required to deposit those funds with an approved depository by the close of the next business day, rather than within the three business days the law now requires. Companies that fail to comply will be subject to steep IRS penalties ranging from 2% to 15% of the underpayment, and perhaps even overdue-interest charges. Below, some defensive precautions:

* Assess your company's payroll-tax risks. Companies that are heavily labor-intensive, growing rapidly, or operating multiple offices may cross the $100,000 threshold sooner than expected. If your company is close to the threshold, carefully monitor your payroll taxes to make sure you don't violate the rules.

* Be certain your internal controls work. Companies that may be vulnerable must calculate FICA and federal-tax withholdings quickly and accurately to be certain of meeting new depository deadlines.

* Investigate your bank's depository policies. "People often assume that all banks have the same date-of-deposit rules, but that's a mistake that can prove costly," warns Robert LeBaube, director of IRS problem resolution for Coopers & Lybrand. To avoid penalties, either deposit withholding tax on the same date your company makes its payroll, or time your deposits to occur before your bank's close-of-business hour the next business day.

* Make deposits with commercial, rather than Federal Reserve, banks. "All Fed banks automatically credit deposits for the next business day, no matter what time they're made during the current day," reports LeBaube. So if your company waited only one day after its payroll to deposit its withholding taxes at a Federal Reserve Bank, it would automatically be subject to IRS tax penalties. -- Jill Andresky Fraser