Every entry below is the rule as China publishes it. It is a reference, not a calendar: where a deadline runs from something only you know, this page says so instead of showing a date.
This is the rule as published by the registry, checked against the primary source on the date shown. It is not your filing date. Where a deadline runs from incorporation, from a fiscal year the company itself elects, or from an event only you know about, no date can be derived here at all — the figure you see is the formula, not the answer. Extensions, transitional regimes and entity-specific exemptions are not reflected. Confirm with the registry before you rely on a date.
The tax year is fixed by statute and is the calendar year: «企业所得税按纳税年度计算。纳税年度自公历1月1日起至12月31日止» — enterprise income tax is computed by tax year, and the tax year runs from 1 January to 31 December of the Gregorian calendar. A company that starts or ends business part-way through a year has a shorter tax year equal to its actual period of operation, and the liquidation period is a tax year of its own. The enterprise annual report to the market regulator is likewise made for «上一年度», the previous year. Because the year is not elected, deadlines counted from its end can be shown as calendar dates; where a record is still marked indicative, the reason is the holiday roll-over and the yearly filing calendar described in that record, not an unknown year end.