Parents sometimes tell lies about their children as occasional drivers
A growing number of people are lying on insurance applications in an attempt to get a better deal, according to the Association of British Insurers (ABI).
Those involved in the fraud are risking their deals being invalidated, as well as putting up the cost of premiums to others, the ABI said.
Common deceptions include failing to disclose a youngster as a main driver or hiding motoring convictions.
Yet the industry admits that "very few" culprits are convicted.
The ABI said a growing number of its members were uncovering cases of "fronting" to get cheaper insurance.
This is when parents add a son or daughter to their motor insurance policy as an occasional driver when the youngster is, in fact, the main driver.
Other issues that could put policies at risk, according to the ABI, are people failing to disclose previous claims or not being honest about how much they smoke or drink on life insurance applications.
"Honesty is the only policy. Cheating to get cheaper insurance puts your cover in jeopardy, with potentially disastrous consequences," said Nick Starling, of the ABI.
"Being truthful and shopping around will mean that your insurance delivers when you need it, and that you get the best possible deal."
He said the vast majority of applicants were honest, but those who lied caused average premiums to be £30 a year more expensive than they needed to be.