Money Saving Expert Martin Lewis has issued a 21-day warning to all drivers in the UK.
He's said that motorists could lose out on as much as £500 if they don't take action in time.
The Money Saving Expert founder was back on ITV for his show on Thursday (October 21) where he told viewers that applying too near the end of your current insurance will hike up prices.
Based on what he had seen, 21 days was the perfect timeframe to grab a good deal, and one happy viewer said she saved half a grand.
His co-host Angellica Bell says: "Loads of people followed that 21-day rule, including Nettie.
"She saved herself £500, which is brilliant."
Martin then explains: "So the 21-day rule... Is if you're coming up for renewal that is the sweet spot to get your new quotes because insurers think you're a low risk then, but if you leave it until the last moment they think you're a higher risk and the price can go up 50% or more."
He also warned that the cost of home insurance is expected to go up in January, says the Daily Star.
The finance guru's weekly newsletter said: "While the new regime officially starts in January, insurers will likely start to shift pricing algorithms sooner.
"EVERYONE with a mortgage should check now if your existing deal is as good as it can get," he wrote in the newsletter.
"That applies double if you're languishing on your lender's standard variable rate."
