Hi Kenyona,
The estimated SE taxes are not calculated in the QBO Accountant version. If your client has a QuickBooks Self-Employed account, he can invite you as an accountant. Then, you can access it using your QBO Accountant company.
Here's an article that explains how the tax is calculated in the Self-Employed version: Estimated taxes explained.
If you have other questions, feel free to join us back here.
Have a good day!