first of all you should eleborate how have you made tha payment without registering.
there are two methods of accounting.
1. book the payment as expenditure and all the receipts/recovery from customers as Sales/receipts.
2. open an account book all the payments, rceipts Cenvat in that account. if every thing goes right end balance should be ZERO.
the Income Tax act recognises taxes as expenditure. you can claim tax as expenditure and even in case of Sales Tax the Interest on Delayed Payment of Tax can also be claimed as expenditure. but all these are subject to sec. 43B, which says that taxes to be allowed only on payment basis. thus in case you claim the tax as expendtiure then your liability of Rs. 10 lacs could not be allowed as expenditure in the same year it will be allowed only if the payment has been made before the due date of filing the return.