Working in Luxembourg, living in France: how your salary is taxed
Luxembourg taxes your salary through the wage tax your employer deducts. As a non-resident you are in tax class 1 by default, even when married; class 1a applies to single parents, widowed people and people aged 64 or over. A married couple can ask for assimilation when at least 90 % of the worker’s income is taxable in Luxembourg or the income from elsewhere stays below 13,000 €; the calculator then uses the collective rate (class 2) only if it is cheaper. Luxembourg social security applies to the whole salary, and health cover is provided by the CNS, with no choice.
Days worked outside Luxembourg — at home in France or in a third country — are tolerated up to 34 days a year. For France the 34 days are reduced in proportion to part-time work or a part year, rounded down, and a part day counts as a full day. Above the threshold, France taxes the pay for all those days from the first day and Luxembourg taxes only the rest.
In France the Luxembourg salary is declared but gives a tax credit equal to the French tax on it, so in practice it is not taxed again; it only raises the rate applied to other household income, such as a spouse’s French salary. No CSG/CRDS is due on it. The comparison shows the net of a Luxembourg resident with the same gross. Not confirmed: whether a non-resident whose pay is partly taxed in France gets the payroll tax credits (CIS, CI-CO2, CIC) in full — the calculator applies them as for residents.