For vacationers renting a car, it’s that deer-in-the-headlights moment. You stroll up to the rental desk and as you complete the paperwork, the agent asks, “Do you want our insurance?” Trust me, this is not the time to ask, “Do I need it?”

Car rental insurance is at best, confusing and, at worst, a waste of your money. Are you covered by personal car insurance? How about a credit card? And if you’re covered, what are you covered for? Here are some tips for navigating the fine print.

KNOW THE LINGO

Most car rental agencies offer at least two basic products — loss damage waiver and liability. Loss damage waiver protects the renter from all financial responsibilities for theft, vandalism, loss or damage to the car. Fees are based on the cost of the car and range from $9 to $36 a day.

Supplemental Liability Insurance protects you from lawsuits by victims of accidents. If you hit a car and someone is injured, a liability policy kicks in and deals with the claimants on your behalf. Supplemental Liability is a flat fee and ranges from $9 to $13 a day, depending on the car rental agency.

You also may be offered additional insurance options. For instance, Hertz sells personal accident insurance and personal effects coverage. That’s a death benefit for the driver and passengers and also covers limited reimbursement for loss of personal property during rental.

Then there’s the infamous “loss of use.” If a vehicle is damaged while you are renting it, you are on the hook. Basically the agency dings you for every day the car is out of service while it is being repaired, in addition to repair costs.

GET PERSONAL

This may not be the advice you want to hear, but the only way to make an informed decision about car rental insurance is to have the facts before you leave home. That means a few phone calls.

If you have auto insurance, call your agent. It’s likely your personal insurance covers you when you get behind the wheel of a rental car. But policies differ as to the amount of coverage, your deductible and other details, says Michal Brower, State Farm Insurance’s Florida spokesman. “Most auto policies cover rentals with the same type and amount of coverage on your personal vehicle,” she says.

Have your agent explain your policy carefully and in detail. Some policies are considered null and void if you violate the rental agreement — have an unauthorized driver or park the car in a bad part of town.

Even if your insurance pays for actual repairs, few policies cover loss of use and/or “administrative fees,” which rental agencies arbitrarily apply when for processing paperwork or handling other tasks after an accident.

“In most cases you don’t need liability coverage, because personal auto insurance covers you,” explains Henry Godwin, executive vice president at MDW Insurance Group in Coral Gables. Also review your homeowners insurance. It may include some coverage, such as liability or property theft.

CARD ME

Once you have drilled down to the basics of your personal insurance, you need to contact your credit card issuer (you’ll find the customer service number on the back of the card). Visa, MasterCard, American Express and Discover all offer some car rental insurance, but it varies not just from brand to brand but card to card, says Beverly Harzog, an independent credit card expert.