Sales return is greater than sales ?what do in 3b

my sales  on  april 2019  is  400000+(18% tax)  b2b supply

may to sep  sales      35000 +(18% tax)

december   sales      15000+(18% tax)    ,sales return  300000+(18% tax)

jan-march  sales       23000+(18% TAX)

THESE ARE MY DATA  

DECEMBER MONTH SALES RETURN EXCEEDS SALES 

negative figure not entering in 3B  AND I FILED 3B  OUTWARD SUPPLY AS ZERO

SO

we filed as in

3b december   outward supply  -0

3b-january,feb,march  -outward supply-0

STILL  DIFFENCE IN SALES RETURN AMOUNT  (300000-(23000+15000)=262000)

CAN I FOLLOW THIS WAY IN NEXT FY 20-21

BALANCE DEDUCT IN 3B   WHERE SALES EQUAL  262000 IN NEXT 6MONTHS