Next to uncertainty over changing tax regulations, employe misconceptions and disinterest, say employers, are the major obstacles to "modernizing" fringe-benefit programs.

According to a recent Chamber of Commerce study, benefit costs now average about 37 percent of company payrolls -- nearly $7,000 per employe each year. In a national survey by the Opinion Research Corp. for the Wyatt Co., a compensation consulting firm, 48 percent of employes surveyed estimated their employer spent 10 percent or less of their salary on benefits.

Here's a look at some popular fringe benefits and how the IRS views them:

* Four out of 10 companies give employes holiday gifts or bonuses, with the median cash bonus for managers $100; for nonmanagerial staff, $88. Taxable.

* Personal computers for home use is the newest wrinkle in executive perks. A recent survey by the Wyatt Co. indicates about 4 percent (up from zero four years ago) of responding corporations now buy PCs for mid-to-upper level employes, and an increasing number provide interest-free loans for the purchase of home computers. Taxable.

* The use of a company car for business has jumped to 86.2 percent of the corporations, according to the Wyatt Co. survey. Fifteen percent of the companies provide prestigious cars such as stretch limos or Rolls-Royces. Business use is nontaxable; personal use and commuting, taxable.

* Nearly half of the corporations surveyed by the Wyatt Co. provide executives with free financial counseling services, a figure that has doubled in the last six years. Taxable.

* Company-paid first-class commercial air travel has nose-dived in the past four years by almost 20 percent because of economic belt-tightening. Taxable.

* The number of employes receiving educational assistance from employers ranges from 2 million to 7 million, according to figures from the American Society for Training and Development. Proposed taxable by the Treasury Department.

* Incidental perks also are growing in popularity. Two examples: Tobacco Institute employes receive four cartons of free cigarettes each month; the American Council of Life Insurance provides workers annual remuneration for personal fitness improvement. Taxable.