Many companies will begin 1989 by trying to streamline and reduce travel and entertainment costs, one of the largest controllable expenses for many firms.

With airlines making 150,000 fare changes a day, it is no surprise that corporate travel expenses frequently soar out of control, according to American Express travel consultant Judith Dettinger-Gardner.In 1988, American companies spent an estimated $95 billion on travel and entertainment. By 1990, the amount is expected to reach $115 billion.

According to the American Express 1988 travel management survey, travel and entertainment expenses are the third-largest controllable expense for most companies, following salaries and data processing.

Gardner, who oversees the American Express Survey of Business Travel Management, said a company can save 30 percent to 35 percent on travel expenses by requiring employees to purchase the lowest logical air fare when they are traveling on business. "Companies should establish a good travel policy and distribute it to everyone," said Dettinger-Gardner. "Then, they should find a good travel agency to help monitor and control expenses."

Internally, a company can do several things to keep a tighter rein on travel costs. Dettinger-Gardner said it is cheaper in the long run to issue credit cards to employees who travel frequently, rather than offer large cash advances, which are frequently misspent. A small cash advance of $10 or $15 a day to cover tips, tolls and taxis is enough for most trips, she said.

Companies that provide generous meal allowances and do not require receipts for expenses under $25 also encourage travel expense abuse, according to Dettinger-Gardner. She suggests that companies require receipts for any travel or entertainment expense over $10 or $15. And, she recommends that someone carefully check the receipts to make sure they are legitimate.