While adding the discount value , taxable amount is changing , either of any value has no effect on each other. so please resolve this issue as soon as possible.

Hi there, zebamehveen0012-.

Thank you for visiting QuickBooks Community. I'll share details on how tax amount calculated in the sales transactions. Then, to ensure that this won't change when adding discount.

The total tax amount is based on the entire amount of the items in the invoice. That said, once you manually add a discount value after you've entered all the items in the invoice, it will change the taxable amount. 

In order to avoid changing the taxable amount, I suggest setting up a service item as the discount item and apply it to your invoice. This manually calculates the discount amount based on the percentage.

Here's how: 

1. Go to the Gear icon.
2. Select Products and Services.
3. At the top right, click the New button.
4. Choose Service for Products/Services type. Then, complete the information needed.
5. In the Name field, enter Discount. If you plan to create multiple discount percentages, you can enter the percentage and Discount for the name (Example: 5% Discount).
6. From the Sales price/rate field, enter the discount amount as a negative.
7. From the Income account drop-down, select Discounts given account.
8. In the Sales tax category section, it depends on your state if sales tax is calculated after discounts are applied then mark the discount line taxable.
9. Hit Save and close.

Once done, you can now use the discount item in your invoices. I attached a screenshot below for visual reference.

Please refer to this article to see different information on how the Sales page gives you a great at-a-glance view of the status of sales transactions, open invoices, and paid invoices: View sales transactions.

Let me know if there's anything else you need help with. Know that I'm always here to help you anytime. Take care and keep safe!

When  I add discount as item or product or service,  sales column is need to be mentioned when I create it. For customers we are allowing discount so it's an expense for us that doesn't comes under sale. So how can I add discount as product or service. This couldn't be the solution.

Thanks for coming back, zebamehveen0012-.

In QuickBooks Online (QBO), there are two way on how to apply a discount. First, we can add the discount as a percentage or specific amount. Just use the discount field on an invoice or sales receipt. Here's how: 

1. Click the + New Plus icon.
2. Select Invoice or Sales receipt.
3. Add products and services. Then fill out the rest of the form.
4. Choose Discount percentage or Discount value to enter the discount as a percentage or a specific amount.
5. Enter the amount you want to discount in the discount field.
6. If you want to discount the total before you calculate sales tax, s9o0elect the arrow icon next to the discount field.
7. When you're finished, press Save and close.

To add a discount item with a fixed price, just follow the steps and details in the  Add a discount to an invoice or sales receipt in QuickBooks Online article. Let's make sure, we choose the Discount given account in the Income account drop-down menu. Then, select Nontaxable from the Sales tax category drop-down menu.

Also, QuickBooks added capability to assign discount per line item in sales forms (i.e. invoices, sales receipts and credit notes). This is in addition to transaction level discount that was already available. To learn more about this one, see the Discount by line item on invoices and sales receipts article.

Feel free to visit our Manage Customers and income page for more insights about managing your company's income and sales transactions.

I'd like to know how you get on after trying the steps as I want to ensure this is resolved for you. Just reply to this post and I'll get back to you. Take care always.