MoneySupermarket examined common mistakes that can void home and car insurance policies. It found that a quarter (25%) of Brits were unaware that posting an Instagram holiday photo could void your home insurance.

The price comparison website calculated that, with 27.8 million households in the country, this equates to nearly 7 million home insurance policies at risk of being voided.

Meanwhile, a fifth (21%) of those questioned didn’t realise that driving with an unsecured pet could void car cover.

With 38.4 million drivers in country, this equates to nearly 7.7 million car insurance policies at risk of being voided.

The Highway Code states that animals need to be ‘suitably restrained’ to ensure they don’t distract the driver, and recommends either a seat belt harness, pet carrier, dog cage or dog guard in order to do so.

Top five ways people have unknowingly voided their home insurance:

• Leaving a window open when leaving the house/flat (31%)
• Posting a picture on social media while on holiday (25%)
• Putting your house up for sale without notifying your home insurer (20%)
• Renovating your house/flat without notifying your insurer (17%)
• Leaving a door unlocked when leaving your house/flat (16%)

Top five ways people have unknowingly voided their car insurance:

• Driving with a pet on the seat unrestrained (21%)
• Changing jobs and not informing your insurer (19%)
• Having an accident that has damaged your car and not informing your insurer (14%)
• Moving to a new house and not telling your car insurer (9%)
• Providing an insurer with an incorrect mileage estimation (9%)

Kate Devine, insurance expert at MoneySupermarket, says: “It’s always important to make sure you understand the key provisions of your home and car insurance policies to ensure you’re not caught short.

“Our research shows that acts that might seem innocuous – such as posting a holiday snap online or driving with your dog in the passenger seat – could void your home or car cover and that many Brits are unaware this is the case.

“If you haven’t read your policies for a while, re-read them to familiarise yourself with the terms and ensure that you’ve got the right cover for your needs. If you haven’t, shop around for a better deal – you could save up to 44% on your home insurance and up to £285 on your car insurance.”