You can set credit limit for Sundry Debtors and Sundry Creditors in Tally.ERP 9.
When outstanding amount exceeds the credit limit, Tally.ERP 9 will not allow any invoice beyond that limit unless modified.
Example :
You can set credit limit of Rs. 40,000/- for the customer’s ledger and raise one invoice amounting to Rs. 2o,000/-, subsequently you can also try to raise another invoice amounting Rs. 25,000/-
To enable credit limit, set Maintain Budget and Control to Yes in F11 > Accounting Features
To set credit limit for customer :
Go to Gateway of Tally > Accounts Info > Ledgers > Ledger > Set the credit limit
After the first invoice is raised for Rs. 20,000/-, try to raise the second invoice for Rs. 25,000/-. Here, Tally.ERP 9 will restrict from saving the voucher