Ow Clev

Hi, I have a chargeable event certificate from liquidating a life insurance policy of 18 years. The gain was circa £11,000 and takes me into the higher rate tax band due to a salary of £44,000. On the form I have entered the amount with tax treated as paid as £11,000 as 20% basic rate has already been taken as per the certificate. However the top slicing relief is only ~£750 leaving a remaining £1,000 bill. As I had £6,000 of margin before I entered the higher tax bracket, surely just 3 years of top slicing would be sufficient, and certainly 18 years should be enough?