Under certain circumstances, partners in a civil partnership formed in Luxembourg or abroad may, at their request, opt for joint taxation. They will then be eligible for taxation in tax class 2 for the entire tax year.

In tax class 2, tax is calculated using the 'splitting' method:

• the partners' income is aggregated;
• this aggregate income is 'split' in 2 halves;
• the base rate is applied to each half of the aggregate income;
• the 2 tax liabilities are then added together.

Taxpayers who are taxed jointly are jointly and severally liable for the payment of tax.

Implications with respect to tax cards (employees or pensioners)

Where both civil partners are employees in Luxembourg (or both receive a pension that is taxable in Luxembourg), they are not required to carried out any particular formalities with respect to their tax cards in the event of civil partnership.

The same is true if only one of the civil partners is an employee (or pensioner) in Luxembourg.

Neither of the civil partners employed (or receiving a pension) in Luxembourg is eligible for taxation in tax class 2 while their tax card is being issued or amended, regardless of whether their civil partnership has existed for the entire tax year or not.

Implications with respect to the income tax return

Under certain circumstances, partners in a civil partnership may, at their request, be taxed jointly by filing a tax return. They would then be eligible for taxation in tax class 2.

To be taxed jointly, the civil partners must satisfy the following conditions:

• at least 90 % of the non-residents civil partners' worldwide (domestic and foreign) income must be liable for taxation in Luxembourg (50 % of their earned income in the case of civil partners residing in Belgium). The 90 % threshold can be calculated by reference to the partners' individual situation;
• the partners must opt to be treated as resident taxpayers. This means that they must report all of their income earned in Luxembourg and abroad, and that they would then be eligible for the full tax relief that is generally reserved for residents;
• the civil partners must request to be taxed jointly by ticking the corresponding box in the tax return, and both must sign the tax return;
• the civil partners must have shared a common home (or residence) for the entire tax year;
• their civil partnership must have been in existence for the entire tax year.

Civil partners may not be taxed jointly for the year in which the civil partnership is registered, or for the year in which the partnership ends.

When civil partners file their first request for joint taxation, they must enclose, with their tax return, the document issued by the relevant authorities in the state in which the civil partnership was registered, attesting that the civil partnership had existed for the entire tax year in question. Note that the 3 countries that have borders with Luxembourg all recognise some form of civil partnership, namely:

• France: the civil solidarity pact (pacte civil de solidarité or PACS);
• Belgium: the legal cohabitation contract (contrat de cohabitation légale);
• Germany: the registered partnership (eingetragene Lebenspartnerschaft).

In filing their tax return, civil partners must report all of the income (domestic and foreign) they earned in the year. They are eligible for the following tax benefits in particular:

• double tax relief (for example, EUR 672 x 2 for insurance contributions and premiums);
• the extra-professional allowance of EUR 4,500 per year. Where the tax liability does not cover the whole year, the allowance is reduced to EUR 375 per full month of tax liability.

Extra-professional tax allowance

The extra-professional allowance applies to civil partners:

• who both earn income from a professional activity in Luxembourg or abroad (business profits, profits from agricultural or forestry-related activities, earnings from self-employment or income from paid employment), and who are individually affiliated with a mandatory social security scheme;
• where one of the partners earns profit from a business enterprise or earnings from self-employment, and the other partner is registered as an 'assisting spouse';
• upon request, where one of the civil partners has been receiving, for fewer than 3 years at the start of the tax year in question, income from pensions or annuities, and the other partner earned profit from a business enterprise, agricultural or forestry-related profit, earnings from self-employment or income from paid employment.

The extra-professional allowance is granted automatically by the Luxembourg Inland Revenue (Administration des contributions directes - ACD). Consequently, the civil partners do not need to apply for the allowance in their tax return.

On the other hand, where one of the civil partners has been retired for fewer than 3 years and the other civil partner receives earned income, the extra-professional allowance can be claimed by ticking box P2 on page 8 of the tax return.

Civil partners who have requested joint taxation for a given year may withdraw their request on an individual basis provided that the tax assessment for the year in question has not yet been issued.

Civil partners who do not file a joint tax return can file a tax return individually to report their own income. In that case, they will not be taxed jointly and each civil partner will be taxed in class 1 or 1A, as applicable.

Implications with respect to the annual-adjustment procedure

Civil partners who do not wish to be taxed jointly, or who do not satisfy the 5 conditions required for joint taxation (see above), will be taxed individually as if they were single.

If one civil partner fails to submit a tax return, they can submit an application to have the tax withheld from their salary (or pension) adjusted by means of an individual annual adjustment.