Hi Gishan Don Ranasinghe,
You declare the dividends in the tax year that you receive them.
Dividends paid by your company Feb to Feb, should be declared in the tax year that you received them.
Eg. Feb 2020 to Feb 2021 should be declared in 2020 to 2021 Tax return.
You can amend your 21/22 tax return up to 31 January 2024, after which you will need to submit an overpayment relief claim,(OPR) using the format shown here:
SACM12150 - Overpayment relief: Form of claims.
After 6 April 2024, it will be to late to claim OPR for 2019 to 2020.
Thank you.