When two people marry they usually combine their finances just as they have combined their lives. When renting or purchasing a home it's customary to put both names on the mortgage or rental agreement. You pay your bills out of a joint checking account for electric and other household bills. What about auto insurance policies; do you combine two separate policies into one?
It is true that having multiple cars on one policy does benefit you with discounts. Even with great discounts, there are reasons to have separate policies. When shopping for insurance quotes online, you will be able to compare rates for car insurance from many different providers.
When an auto insurance policy is written there is always a principle driver listed. Secondary drivers can be listed on the policy but are charged a lower rate because they do not drive the car very much.
If one driver in the family has a bad driving record with accidents, tickets or other violations; or has bad credit it would be cheaper to keep them off the policy and see that they have their own separate policy. In this case avoiding a combined policy would keep the rate lower but check with your insurance company for actual insurance rates.
Having an expensive car and listing it as only having one driver would save money. Have only one spouse be the specified driver of the vehicle because adding a spouse would just increase the cost of insurance.
When one spouse has bad credit it can drive the cost of car insurance up. Insurance companies check your credit report when you apply for car insurance. They have the right to see your report because if you are late with bills or in default, it reflects on your ability to pay. Also think you are a higher risk for them because your credit is bad. If it is bad you will be paying more in insurance premiums.
It's best to check with your state insurance regulation because it may be mandated that both spouses must be on the same policy.