Optional (non-)filing and effective taxation

Many countries have automatic wage tax withholding systems with tax non-filing options for some taxpayers. We show that this has sizable and potentially unintended implications for effective taxation because taxes are often over-withheld. Low-income taxpayers pay more taxes than they have to because they frequently do not file. Using German administrative tax data, we document that the average non-filer overpays € 119 in one year, equivalent to a 1.2 percentage point increase in the average tax rate. Non-filing acts as a form of "reverse evasion": It weakens the effective tax progressivity by increasing tax rates at the bottom of the income distribution.