A chargeable event & tax

Grable

My mother died earlier this year, leaving a life insurance policy which she had taken out 11 years ago. It named me, my brother and her as lives insured. My brother and I have now cashed in the policy, which has given us a sizeable chunk of cash as a 'chargeable event' for tax purposes. The combination of the gain and my normal income hasn't brought me to the higher tax rate threshold - at least I don't think it has, although I'll need to check the interest on my savings.
Because my income is usually PAYE only and I have nothing to claim for, I don't usually fill in a tax return. I'm wondering, though, if I should this year in view of the 'chargeable event'. And if I should, when does it need to be done? The gain was made in September this year.

[Deleted User]

You would only need to inform HMRC if the chargeable event brought you into higher rates iof tax. Even then there may be top slicing relief available. More details of income and the chargeable event details needed.