At this time you are filling your GSTR 1 for the month of July and after that on 20th of this month you are going to fill your GSTR 3B for the month of July and in this you will deduct the input received from the tax collected by you and will pay tax.
Your vendors who fill their GSTR 1 generate your GSTR 2B which mentions the inputs received by you and Input credit available in same GSTR 2B can be claimed as per rules. If your seller has not filed his return on time or has not given you this credit, then as per rules you cannot claim it.
Now the process has been done very clear.
1- If you have taken input credit in your GSTR 3B in excess of the input credit shown in .2B, you will automatically get a notice generated by the system and the same notice will also be sent to your registered e-mail in the GST network.
2- You have to reply to this notice in 7 days and for this you have only two options either reply to this notice or pay the difference.
3- Now if you do not respond to the notice or do not submit the excess claimed inputs in this manner, then your next month’s GSTR 1 will not be allowed to be filed. This is provided for in a separately applicable Rule 59(6).
Similarly, the facility of uploading invoices on the portal of dealers filing quarterly returns will also be stopped.
4- If your answer is not found appropriate by the proper officer, then he will take action against you under section 73 or 74 of GST as per rules and for this he will issue notice.
So, file your GST Returns very carefully.