With the exception of the canton of Valais, interest on loans, whatever their form (building loan or mortgage), is not deductible during the construction period.

In the cantons of Vaud and Geneva, for example, interest on the building loan is considered as an investment cost and therefore cannot be deducted from taxable income. In the event of a sale, the investment costs will be deducted from the sale price to calculate the real estate gain realized. 

Articles on taxation:

• Marginal tax rate
• Transfer duties
• Rental value
• Tax on real estate gains
• Real estate gains
• Land tax
• Maintenance costs
• Standard deduction
• Limitations to debit interest deductions
• Annuity from the right to land occupancy
• Distribution of interest expense
• Life insurance financed by third party funds