Depending on the type of contract established with your company.
Unused budget is either:
Carried over to the next month and therefore you will be able to spend your normal amount plus the remaining amount of the previous month.
If your company has chosen the "top-up" option, the unused budget is topped up at the end of the month and you have the same budget amount at the beginning of each month.
Open your NAVIT app, tap the "?" in the top right corner, then select "Your Mobility Benefits" — or reach out to your benefit manager or check your intranet for more info.