How is the deductible interest charge prorated?

For the 2024 tax year:

No prorata calculation is made for the 2024 tax year.

For the 2023 tax year:

The calculation of deductible interest expense is based on a number of factors, including :

• the date of acquisition of the property
• the date on which you moved into the property
• the interest paid on the mortgage
• the interest ceiling.

Here are 2 examples:

A couple (married or civil union) bought a house on 01/04/2023 and moved in on 01/07/2023.
They paid interest of €10,000 in 2023.
The ceiling to be applied is €6,000.
Non-occupancy period: 91 days
Days to end of year: 275

Calculation details :

Field 1017: __
10,000 * (91 / 275) = €3,309.09

Field 1021: __
10,000 - 3,309.09 = €6,690.91
As the €6,690.91 is greater than the €6,000 ceiling, the ceiling must be applied.

Field 1029: __
3,309.09 + 6,000 = €9,309.09

A single person bought a house on 01/04/2023 and moved in on 01/07/2023.
He paid interest of €5,000 in 2023.
The ceiling to be applied is €3,000.

Non-occupancy period: 91 days
Days to end of year: 275

Calculation details :

Field 1017: __
5,000 * (91 / 275) = €1,654.55

Field 1021: __
5,000 - 1,654.55 = €3,345.45
As the €3,345.45 is greater than the €3,000 ceiling, the ceiling must be applied.

Field 1029: __
1,654.55 + 3,000 = €4,654.55

Updated on: 19/10/2026