Excess Payment in March

Bala Sundaram (84 Points)

14 April 2020  
Dear Experts
Bill was raised and sent to customer at correct amount and rate. Inadvertently in GSTR 3B excess taxable amount and excess GST was paid. In GSTR 1 correct amount will be filed. How can the excess paid will be adjusted. Since it can't be adjusted within the financial year whether it can be adjusted in the next financial year. There will be difference between GSTR1 and GSTR 3B.
Or we have to apply for refund. Pl clarify and relevant section of the Act
Thank you.