Like so many aspects of modern business, travel expense reimbursement and management has its gray areas – those infrequent but often vexing issues that confound managers and defy policies. Just when it seems we have learned how to handle just some of them, new ones come along.

Gratuities have long been an area of discussion in travel expense management, as have those small personal trips employees inevitably take during the workday. Now new models for business transportation, such as the car sharing services now gaining popularity, give us still more food for thought.

Gratuities: The rule is have a rule

Questions of whom to tip and how much to give them are hard enough in our non-working lives. On the job there is the added pressure of wondering whether or not an employer will reimburse the cost. Further complicating matters is the fact that many companies, especially larger ones, are fairly relaxed about gratuities given on corporate cards.

But should an employee be allowed to tip more than normal for exceptional service? Is that decision one an employer should be expected to endorse? What about tips paid in cash for which there is no receipt? These might be paid to a hotel shuttle driver, valet, porters, concierges, room service deliverers and housekeepers.

The rule here is to have a rule. A T&E policy can be written to specify, for instance, that gratuities will be reimbursed up to a predefined percentage of the total bill. While that is a straightforward approach for restaurant meals and taxi and chauffeur services, it’s less well-defined for services from doormen, porters and housekeepers. Again, the key is to have a policy.

Small personal trips: Follow IRS guidelines

Small personal detours while on business, such as driving to lunch while out of the office on business, are inevitable. They are common enough to be governed by IRS rules that cover infrequent, occasional situations. The IRS even defines infrequent.

“Infrequent personal use is generally less than one day per month,” according to IRS revenue agent John Darr, who addressed the topic in an IRS webinar that discussed what the IRS calls de minimis use.

“Say an employee uses a government motor pool vehicle for a business meeting. The government requires employees return motor pool vehicles at the end of the business day, but the employee is delayed and the motor pool is closed when the employee arrives back at the office. The employee takes the vehicle home and returns it the next morning. Assuming that this is an infrequent occurrence for that employee – generally happening no more than once a month, the commuting value of the trip is a nontaxable de minimis fringe benefit.”

Car sharing: New services demand new policies

Car sharing has introduced a new wrinkle to travel expense reimbursement. In this scenario, vehicles are managed by a third-party company. Employees have individual subscriptions to the service and can reserve vehicles as needed. Is this a reimbursable expense? There seems to be little guidance available yet on this question, though the services themselves would seem motivated to provide it. Some, among them Zipcar, offer business memberships with lower rates and automatic billing.

Whatever the question, organizations can’t be shy about demanding answers from the provider of their travel expense management solution. Adding functionalities as new scenarios emerge improves expense management and makes for better solutions and stronger relationships between customer and provider.