Gst sac code - issue

00440092 this is service tax payment code , 

SAC code is 998221, use this for billing

BUT AT THE TIME REGISTRATION THE 998221 IS NOT AVAILABLE @ PORTAL 

HOW TO ADD SAC CODE 998221 @ GST PORTAL 

BECAUSE @ THE TIME OF REGISTRATION  >>  THE GOODS/SERVICES BOX 

THERE IS NO OPTION TO ADD 998221

ONLY IT SHOWS THE CHARTERED ACCOUNTANT SERVICES 00440092

in  GST registration window you will find only service payment code. No sac code are there in the registration window. you can raise invoice with the sac code as above