Is there anything special to take into account if I'm going to change my tax deduction card during the year?

It is important for you to report what you have earned and what tax you have had deducted from January up until the time you apply. You will find these details on your last payslip, or by adding up the amounts on all your payslips/pension payments. You must also report your annual income and other income and deductions. The amounts must be stated gross.

You can amend your tax deduction card here.