To view your tax account, log into myTax portal details, click on ‘View Details’ of the tax type for which you would like to view more details or download the Statement of Account.
The payment should be reflected as "e-payment" and it will take 3-5 business days after the payment due date for your IRAS account to be updated.
Screenshot below shows how will it be shown on your IRAS statement, as an indication that the payment is made through CardUp.