To save yourself some money, start by asking this question.

When’s the last time A/P updated your company’s travel policy?

According to research from Expert Insights and American Express, most businesses put off the practice. In fact, less than one-third of A/P pros have reviewed their T&E policies in the past 12 months.

Of course, your finance people probably give yours a routine look when IRS issues its new mileage rates or per diems, but leaving other areas untouched could cause the bulk of travelers’ expense report errors.

Explain what’s not covered

Even if you think your T&E policy clearly explains what expenses are reimbursable and what’s not covered, there’s a simple maxim to follow: If it’s not explicitly pointed out, travelers will assume an expense is OK.

Case in point: 80% of policies don’t address reimbursements for ancillary fees, including checked bags, changes to flight reservations, hotel extras, etc.

Extra fees such as these can send a run-of-the-mill expense report total into the stratosphere, all because your travelers thought they were covered.

If your company has a section in its policy stating whether or not these extras will be reimbursed, that’s a good start – but you need to give your travelers more info.

Instead of a small notation, flesh out the section and give them plenty of examples of fees and extras. It’ll prevent rogue expenses from showing up on T&E paperwork. And if they do, you’ll have the reason for the reimbursement denial spelled out.

Explaining for first-timers

For your infrequent travelers, you’ll also want to explain how airline and hotel reservations should be handled.

Only 35% of companies require bookings to go through a corporate travel agency, but your company may have preferred vendors to use.

Especially when volume booking discounts are on the line, even a few travelers buying from outside vendors can drive up T&E costs and headaches.