TLDR: The allocation of tax reductions depends on when the marriage or PACS occurs in relation to the tax reduction's triggering event. If the latter precedes the union, the cap remains that of single individuals, and the portions can be allocated on either the individual or joint tax return, depending on the case. If the union precedes the triggering event, the reduction is allocated on the joint return with the corresponding cap.
General allocation rules
Tax reductions related to investments made before marriage or PACS are allocated on the joint tax returns of the couple, but the applicable cap remains that of single individuals. This applies when the triggering event of the reduction (completion or acquisition of the property, subscription, etc.) occurred before the date of the union.
Cases where marriage or PACS precedes the triggering event
If the marriage or PACS takes place before the date of the tax reduction's triggering event, the first portion of the reduction is fully allocated on the tax return of the individual taxpayer who made the investment, with the corresponding cap. If this portion exceeds the taxpayer's gross tax, the balance can be allocated on the joint tax return of the couple.
Cases where marriage or PACS follows the triggering event
If the marriage or PACS takes place after the date of the tax reduction's triggering event, the first portion of the reduction is fully allocated on the joint tax return of the couple, with the corresponding cap. The spouse or partner who made the investment can have the remaining balance of this portion allocated on their tax return as a single individual.
Marriage or PACS in the year of the triggering event
If the marriage or PACS occurs in the year of the triggering event, the first portion of the reduction is generally allocated on the couple's joint tax return. However, if the couple opts for separate taxation, the tax reduction applies to the expenses incurred or investments made by the spouse or partner who made the payment or investment.
Years following the marriage or PACS
If the marriage or PACS is concluded in one of the years following the year in which the right to the tax reduction arose, the taxpayer, as a single individual, can, for that year, take into account the portion of the tax reduction on their individual return and, if applicable, allocate the balance on the couple's return. The applicable cap remains that of single individuals.
Applicable caps
Tax reduction caps vary depending on family status: €50,000 for a single individual and €100,000 for a couple subject to joint taxation. These caps are applied based on the date of the tax reduction's triggering event, not the family situation at the time of allocation.
Uniqueness of the tax reduction
Only one tax reduction can be applied at a time. If the couple decides to continue allocating the remaining portions of a tax reduction linked to a first investment, they cannot benefit from a new tax reduction for a new investment until the spreading period of the first reduction is over.