If you are receiving working tax credits you should be eligible for a one off £500 payment.
The temporary increase in tax credits ends on 5 April and this payment is to provide extra help when it does.
HMRC will make the payment automatically so you do not have to do anything.
You should receive the payment directly by 23 April 2021. The payment is not taxable and it does not need to be declared for self-assessment tax returns or for your tax credit renewal.