Annual Return, corporate tax and XBRL
All three follow a financial year. They go to different agencies on different forms.
Annual Return
The return files company particulars with ACRA. A private company generally files within 7 months after the financial year end. It is not a tax return. The secretary plan includes that government fee, not the preparation of the financial statements.
Corporate tax
ECI and Form C-S, Form C-S (Lite) or Form C go to IRAS, on a different timetable. Buying tax filing does not mean the books were purchased.
XBRL
Some companies file financial statements with ACRA in XBRL. It is a format, not a second set of books and not an audit. Whether it applies, and whether a quote includes it, is confirmed separately.