I recently took a short trip home to Wisconsin to visit my family, and I rented a car for a few days. I’ve done this a few times for trips home, and I’m always a little perplexed by one question at the rental counter: “Would you like to buy our collision coverage?”

In the past, I’ve usually ended up buying the coverage. But before this trip, I started to wonder whether I really needed it. Collision coverage is an extra expense on top of the daily rental rate and gas, and it’s not cheap. So I looked into it to see if I could go without the coverage. As it turns out, you might be doubling up on collision coverage you already have when you purchase a rental-car protection package. You may already have coverage through:

• Your own car-insurance policy. If you already have collision coverage through your personal car-insurance plan, you probably don’t need to pay extra for the collision coverage the rental-car agency offers. Not sure what your policy covers? Give your insurer a call and ask for details about how your coverage would apply to a rental car.

• Your credit card. Many credit card companies offer rental-car insurance to cardholders. However, you may need to have a higher-tier credit card to access this service. Call your credit card company to find out if they provide insurance and if you qualify. And if you’re looking for a card with this benefit, check the options at your credit union first. You’ll likely find the best credit card deal there.

• Your homeowners insurance policy. In some cases, you may even have rental-car coverage through your homeowners insurance plan. You often can extend your liability when you’re not at home. Again, check with your homeowners insurance provider, since options vary from plan to plan.

Do you have other suggestions for alternatives to purchasing expensive rental-car collision coverage? Share your knowledge in the comments.