Usually you'll pay a lot more if you buy your children their own auto insurance. By Kimberly Lankford, Contributing Editor November 1, 2007 Should I put my teenagers on my car insurance or get them their own policies?Put them on your own car insurance. The base rate usually starts out lower, and your multi-policy and multi-car discount can cut rates by another 15%. Meanwhile, boost the liability limits on your auto policy and consider an umbrella policy that can raise your entire family's auto and homeowners insurance limits by $1 million. An umbrella policy tends to cost just about $200 per year, says Jamahl Johnson, of Johnson Family Insurance in Washington, D.C., which is about the same as the savings you'll get from the multi-policy and safety-course discounts. You also can earn discounts if your child has good grades or takes a driver's safety course. For more information about buying car insurance, see our Smart Shopper's Guide to Auto Insurance and The New Math of Auto Coverage. Got a question? Ask Kim at firstname.lastname@example.org.