Making a one-off payment

My son pays higher rate tax via PAYE. He’s just received a one-off payment from an estate planning bond (his grandma died). How does he pay the tax? I understand I’ll get a chargeable event certificate as the sole trustee but I’m not sure what else happens and how we know how much tax and how to pay.

Hi

If your son completes a self assessment tax return, he should declare the chargeable event gains (CEG) on the supplementary page SA101, in the sections for 'Gains from life insurance policies, capital redemption policies and life annuity contracts' on page Ai1 or he should tailor his online return to include this section.  
If he does not need to complete a self assessment tax return, he should send the CEG certificate to H.M. Revenue and Customs Pay As You Earn BX9 1AS.  As a higher rate tax payer, there could be some additional tax to pay.

Thank you