The earliest backdating period for supplementary tax on overseas income is 2017.

Recently, it has been learned from multiple sources that the retrospective period for additional tax on foreign income of tax residents in mainland China has been extended compared to before, with the earliest going back to 2020 or even 2017. Since 2025, many tax residents have received reminders and notices from the tax authorities, requiring them to self-check their domestic and foreign income and promptly file tax returns. The retrospective scope for additional tax mainly covers the past 3 years, with a focus on 2022 and 2023.