Entering expenses for my start in 2025 in the year 2026

I assume the procedure is the same as for an invoice received on 2025 but the period is in 2026.

Then you have to go to the 2026 financial year, at the top right, enter your invoice in the same way, leave the invoice date as 2025, which is required, but uncheck the box "Enter document on this date," then set the fiscal date to 2026, e.g.: 01/01/2026. This will then be included in the costs for 2026 and not 2025. However, if you have already entered the invoice for 2025, you will need to delete it or update it. Hopefully, this will help you a little.