So there will be no problem in paying the money via cheque by depositing the money you receive from builder but the only issue is that you must have some proof to show that from where you deposited such 20 lakh amount in bank?
You must have the source of it.
If you can prove the source there is no issue.
Also now he can't charge you GST as he will show that you have paid money after the construction is complete, so do take note of that.
You can make a consultation session if you want more clarity.
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