Welcome to the Community, @1231 4639 0928 954.
Helping you to get your accounting task done is our priority. However, the option to activate or add Tax collected at Source (TCS) when creating an invoice in QuickBooks Online (QBO) is unavailable. That being said, I recommend reaching out to your accountant to give you the best advice on how you can enter the TCS on the transaction.
If you're not affiliated with one, you can use our Find an Accountant tool. You can also request a free consultation with one of our online bookkeepers to help you with your concern.
I also encourage you to visit our QuickBooks Blog page to keep you updated on the latest news of the product. From there, you'll see newly released features and other resources that'll help manage your business.
Also, to provide you more info on how GST works, see this link: How GST impacts QuickBooks users.
The Community is always open if you have further concerns about adding TCS on invoices in QBO. Just post a comment below to notify me of your response. Have a good one.
