Is there any tax required to pay the annual fee at the Patent Office?

No need.

The annual fee payment method is as follows: the date of issuance of the authorization notice issued by the Patent Office plus 3 months is the authorization date. For invention patent applications, the grant date is after the due date of the maintenance fee. Since the maintenance fee for the current year has been paid, the patentee does not need to pay the annual fee for the current year. If the authorization date is before the payment due date, the maintenance fee for that year should be regarded as the annual fee. The annual fee shall be paid every year thereafter before the due date of the annual fee.

Tax point, the abbreviation of tax threshold, also known as tax starting point or tax threshold, refers to the starting amount stipulated in the tax law that taxable objects start to be taxed. If the amount of the tax object reaches the threshold, the entire amount will be taxed; if the amount does not reach the threshold, no tax will be imposed.