Within six months (as from the third working day) following the date of sending of the tax assessment notice by the Belgian tax authorities, taxpayers can file a tax claim in order to obtain a rectification.
After this six-month period has expired, a rectification in case of surtax can in some cases be requested via an ex-officio tax relief during a five-year period. This is for example possible in the following cases:
– In the case where a tax reduction was not claimed or granted;
– in the case where a ‘material error’ was made when filing the tax return or when establishing the taxes due.
Due to a change in the tax law in December 2013, the list of tax reductions eligible for such ex-officio tax relief was significantly extended as from tax year 2014 (income of 2013).
Recently, the Belgian tax authorities have published a Practice Note including a list of all eligible tax reductions. They have also clarified the notion of ‘material error’ with specific examples of (non-)qualifying material errors. It is e.g. explicitly stated that wrongfully declaring foreign-source income as Belgian-source income, does not constitute a material error.