Miranda Puttock

Good afternoon. Like others on this thread, I am a UK tax payer, and receive regularly (several times per year) vestings of RSU in the US. So far my company has treated each vesting as a taxable gain, and deducted all taxes related to this gain from my monthly pay. They are now proposing a "sell to cover" and will pass the proceeds of the sale of the RSU (enough to cover taxes) on vesting date directly to me, outside payroll. My payslip will therefore remain the same as before - showing the full amount of taxable gain, and the full tax deduction made to cover all due taxes. How do I declare the money received from my company which isn't included in payroll, but is the proceeds of selling RSU? Thank you.