Just like for most official issues, expats can complete their tax declaration (Belastingaangifte) online:

Annual Dutch tax form steps

• Apply for a DigiD.
   
• Look at your Jaaropgave (last-year overview of your income obtained by your employer) and highlight: gross salary (Fiscaal loon), tax & insurance contributions (Loonheffing), and Tax credits (Arbeidskorting) if applicable.
   
• Visit the website of the Belastingdienst (Dutch tax office), download the official program (available for MAC, Windows & Linux) and fill in the key numbers mentioned above (Gross salary, tax and insurance contributions as well as tax credits) in the Werk en woning section (left sidebar).
  
  Alternatively, first fill in your personal data and income details and then press Overzight before sending your form to the Dutch tax office. The box next to Te betalen will specify whether you qualify for a tax return or you are obliged to pay a supplementary amount.
   
• Enter your digital signature and a notification form (receipt) will be sent to you a few days later.

Note that the above procedure is based on the hypothesis that you have not bought a house or have other sources of income apart from your main work.

Facts & Tips about the annual Dutch tax form

• The Dutch tax rate system is one of the highest in Europe.
• The whole procedure must be completed by April 1. Nevertheless, extensions are possible.
• Tax officers are not allowed to speak English on the phone!
• You can always consult a Dutch tax expert.
• Those who started working few months before the end of the year can qualify for full tax return.
• Sooner or later, all professionals will receive the blue envelope.