A withholding tax system that was previously announced as taking effect as of January 1, 2018, went into force on January 1, 2019. The new withholding requirement will apply to many income types, including employment income. The rate of withholding is determined by the tax authorities based on prior tax returns submitted by the taxpayer. If the taxpayer is not on French payroll, the taxpayer is personally responsible for remitting tax on 2019 and future year income monthly. Because in the prior system tax payments were made in arrears (tax due on 2017 income was paid in 2018), there will be a transitional adjustment in 2019 for tax due on income earned in 2018 that historically would have been due in 2019. To avoid a double tax burden on 2018 and 2019 income during the same year, taxpayers will be entitled to claim a credit on “regular” income earned in 2018, effectively eliminating income tax on 2018 regular income. However, tax will still be due on “exceptional” income earned in 2018. This change in tax collection will potentially have a significant impact on global mobility programs and administrative processes, especially during the transition period.