Hi Annie Qu,
Thank you for your question.
Please refer to our helpsheet
HS300 Non-residents and investment income (2023) which provides more information about non-residents and investment income and how it is charged to tax. Non-residents are not taxable on UK dividend income but this should still be declared if completing a Self Assessment tax return, for calculation purposes this will show as ‘Non-UK resident’s disregarded income’.
More information about double taxation and investment income can be found in
SAIM1170 - Savings and investment income: non-residents.
Thank you.