Including Taxes
All fees in Matukio include taxes by default, if you want you can also change this in the Matukio configuration to just show net fees.
Payment processing
If you disable payment processing, the fees are still shown and the event can still be booked, but no payment processing will take place for the booking.
Custom Fees Relations
Custom Fees are always relative to the default fee. When you update your default fee all other fees are adjusted too. Custom fees can be either entered as a percentage or an absolute value in relation the normal fee.