For One invoice, how can I record 50% as paid and balance as bad debt?

I get your point, @neethal. I’m here to provide the best way to manage your receivables and write off bad debt in QuickBooks Online.

The initial invoice is left unpaid when a customer only pays a portion of the total amount. To settle the balance, you can record the partial payment and write off the bad debt.

Here’s how:

1. Go to the + New, then select Receive payment.
2. Select the customer's name from the Customer dropdown.
3. Choose one in the Payment method dropdown menu.
4. From the Deposit to dropdown, select the account and enter the amount in the Amount received field.
5. In the Outstanding Transactions section, locate the invoice you're recording the payment on.
6. Hit Save and close.

See this article to learn more about receiving invoice payments: Record invoice payments in QuickBooks Online. This includes the steps to edit or delete and to group multiple payments together.

Afterwards, let's launch the Accounts Receivable Ageing Detail report. This will help us track all uncollectible invoices from your customer. I'll show you how: 

1. On the left pane, select the Report menu.
2. Enter the said report in the search box.
3. Click Customise, then filter the necessary fields.
4. Hit Run report.

Next, let's set up a bad debt expense account by following these steps:

1. Go to the Accounting menu, then choose Chart of Accounts.
2. Click the New button.
3. Select Expenses in the Account Type drop-down menu. 
4. From the Detail Type, tap Bad debts.
5. Click Save and close. 

Then, you'll need to create a non-inventory item to balance the accounting. Let me show you how: 

1. Go to the Sales tab, then select Product and Services.
2. Click New and choose Non-inventory. Then, enter the necessary info.
3. In the Income account ▼ drop-down, select the Bad debts you previously created.
4. Press Save and close.

Once done, create a credit note to write off the transactions. Follow the instructions below:

1. Click +New, then select Credit note. 
2. Pick the customer from the Customer ▼.
3. Select Bad debts in the Product/Service section.
4. Enter the amount of the other 50% unpaid transaction and hit Save and close.

To proceed with linking the credit note to the unpaid portion of your invoice, go to Step 5: Apply the credit note to the invoice section in this guide: Write off bad debt in QuickBooks Online. Lastly, you can continue to Step 6: Run a bad debts report on all the receivables you tagged as uncollectible. I've added snippets below:

I've also attached some resources that will walk you through personalising your sales forms and reports in the program:

• Customise invoices, estimates, and sales receipts
• Customise reports in QuickBooks Online

Please know that you're always welcome to post a reply in this thread if you have any other questions about recording invoices. I want to make sure that this concern is taken care of. Stay safe.