Generally speaking, cash or equivalent means of payment (traveller’s cheques, savings books, cheques, stocks, interest coupons, bonds, bills of exchange, negotiable promissory notes) of a value in excess of €10,000 must be registered. However, a distinction must be made in the type of registration, depending on the areas of travel. The registration is submitted orally for travel within the EU. In the case of travel from an outside country to an EU member and from an EU member to an outside country, means of payment in excess of the above amount must be registered in writing. The written registration form must be submitted in the area of the customs inspections marked in red. If you are carrying this amount of cash and leaving the EU, the declaration must be submitted before going through the security checkpoint. Follow the signs pointing the way to the proper customs office.
Additional information is available on the customs office internet site.