Hi StockOptions821485a,
Restricted Stock Units, are a way of employers providing incentives to employees over the long term.
As the RSU is from your employer, the income when it vests, should be shown in the employment section if it is included in your P60.
You would then claim a credit for the tax, in the foreign section under 'Employment, self-employment and other income which you paid foreign tax on'.
If it's not included in your P60, please include it on the box on the employment page for 'Tips and other payments not included on your P60'.
If you do not sell the shares immediately on vesting, then you could have a capital gains tax liability, where they are sold for more than the acquisition cost.
ERSM20193 advises that when RSUs payout at the market value on what is called "dividend equivalents" in either cash or shares, such payments will generally be taxed as earnings in the year they are received.
ERSM20193 - Employment-related securities and options: what are securities: RSUs and dividend equivalents.
Thank you.