The sewage treatment fee shall be approved in accordance with the principle of compensating the operation and maintenance costs of sewage pipe network and sewage treatment facilities and having reasonable profits. The taxable variety of sewage treatment fee is the income from engaging in qualified environmental protection projects. From the tax year when the project obtains the first income from production and operation, the enterprise income tax will be exempted from the first year to the third year, and the enterprise income tax will be halved from the fourth year to the sixth year.