Physiotherapist practice deduction

Dear Sir/Madam,

I enter my full monthly income on Dexxter as a physiotherapist. I then enter the percentage deducted by the practice where I work under expenses. I was wondering whether this is considered a professional expense when you fill in your taxes? Or do you simply enter your income with this expense already deducted and enter the normal expenses as professional expenses? Otherwise, I would prefer to enter fixed professional expenses, as I don’t incur many expenses yet and this would be more advantageous. I hope this question is clear and that someone can help me with this.