If you have received a prison sentence of more than four years, your conviction will never become spent and you must declare it.
If your conviction is spent, you do not have to mention it when applying for insurance.
It’s important to know that if you have an unspent conviction, and then receive a further conviction, neither will become spent until the longest of them does.
If a second conviction results in a sentence of over 4 years, then no conviction will ever become spent.
Find out what time it takes for main sentences to become spent here.