I received advance payment from customer . Invoice issued for part payment next day. Please assist in mKING ENTRY FOR THE SAME

Great having you join us here in the Community, @kunal.jain. I’d be more than happy to share details about your concern. 

There are ways to handle credits in QuickBooks Online. One is to create a credit memo for your customer's advance payment.

Here’s how to create a credit memo:

1. Select + New.
2. Select Credit note.
3. In the Customer dropdown, select the customer's name.
4. Enter the credit note details, such as the date and the amount. You can create a custom credit service item so you can quickly add it to credit notes as a single line item.
5. When you're done, select Save and close.
   
   

 After that, you can manually apply a credit memo to an invoice.

Here’s how:

1. Select + New.
2. Select Receive payment.
3. In the Customer dropdown, select the customer.
4. In the Outstanding Transactions section, select the open invoice you want to apply the credit note to.
5. In the Credits section, select the credit notes you want to apply.
6. For the open invoice in the Payment column, enter how much of the credit you want to apply.
7. Leave the Payment method, Reference no, Deposit to, and Amount received fields blank.
8. Fill out the rest of the form, including the Payment date.
9. Make sure the total is correct after applying the credit note.
10. When you're done, select Save and close.

 
Moreover, you can also check this article for more details on how to create and apply credit notes in QuickBooks Online.

If incase your customer wants a refund, please see this link for further details.

Please let me know if you have any questions about credit memo. I'll be right here to help. Wishing you the best.