According to Article 54 of the Enterprise Income Tax Law, an enterprise shall, within five months after the end of the year, submit the annual enterprise income tax return to the tax authorities for final settlement and settlement of the tax refund. Article 129 of the Regulations on the Implementation of the Enterprise Income Tax Law stipulates that an enterprise shall submit the annual enterprise income tax return, financial and accounting reports and other relevant materials required by the tax authorities within the time limit stipulated in Article 54 of the Enterprise Income Tax Law, regardless of whether it is a profit or a loss during the tax year.

Therefore, according to the above provisions, enterprise income tax should be settled annually during the preparation period.