Itc claimed under wrong head and paid tax after offsetting .

Dear Sir

While filing January month GSTR 3 B, One of interstate purchase credit IGST wrongly shown as CGST and SGST input and paid Tax after adjusting CGST & SGST input. Tax paid under CGST-2500, SGST- 2500. If IGST input shown correctly Tax payable would be Under SGST- 5000 only.

Now What correction should be done in March month GSTR 3 B. In march I have input credit SGST-10000 CGST- 10000/-  . Reversing earlier Excess CGST & SGST input from that  and adding IGST in GSTR 3 B is enough or I need to pay tax on January month Shortfall in SGST Tax 2500 (5000-2500)

Please Clarify.