Welcome to QuickBooks Community, info1178.

Tax collected at Source or TCS is calculated based from the Sales value or (Scrap Value + GST). In QuickBooks Online (QBO), TCS is not automatically calculated. Instead, you can add a line item for its calculation where you can manually enter the calculated TCS deduction on the bill.

To create an item, please follow the steps below:

1. Go to the Sales menu and select the Products and services tab.
2. Select New. Choose Non-inventory or Service.
3. Fill in the information needed. Then, click Save and Close.

I've got you this article for additional information about adding product and service items to QBO: Add product and service items to QuickBooks Online.

Once done, you can now apply the TCS deduction item on your Bill:

1. Go to the +New icon.
2. Under Suppliers, choose Purchase Bill.
   
3. Under Item details, apply the TCS item and enter the amount in the field provided.
4. Click Save and close.
   

While the option for automatic calculation of TCS deduction on bills in not yet available, I encourage you to visit out QuickBooks Blog. Updates and latest feature will be posted and shared there.

If you have other questions, just let me know. I'm always happy to assist you further. Have a great day ahead.