You always pay tax and national insurance contributions on your wages: this is called payroll tax.
Kolibrie withholds this payroll tax from you, but payroll tax is not deducted from all income from paid employment.
For example, no payroll tax is processed on "tips".
You must therefore do this yourself during the pay return for the past tax year.
For more information about tips and the payroll tax that you have to pay, we refer you to this page.