Hi Raghav,
The WHT data is stored in table WITH_ITEM. You can see the detail in here.
Example:
I have one vendor with 2 WHT types at payment:
I created one invoice, with different tax code for each WHT type. Doc no is 1900000002
If I check doc in table BSEG, I will see WHT base amount is 2,000. It's total tax base amount in document.
But, when I check in table WITH_ITEM, I will see the tax base amount detail for each tax code.
So, you can check your document in this table.
Julie