The European Commission adopted the Euromarker (SY124) in 2001 as a common pan-European fiscal marker to label gas oil and kerosene. In parallel, several other marking systems based on other dyes and markers were already in use in different member states. Generally the use of a marker makes it possible to sell fuel with a lower tax for use in dedicated sectors like agriculture, marine use and for domestic heating. In contrast, non-marked fuels are normally fully taxed and intended for road transport. Unfortunately SY124 is easy to remove or destroy which has made wide-spread fraud possible. This has resulted in substantial losses of tax revenue and a number of member states have repeatedly notified the European Commission of this problem. Some member states currently invest considerable amounts of resources and effort in tracking illegal use of laundered fuel by performing >10,000 measurements per year of SY124 in gasoil and diesel. Other member states have recently adopted a new national marker to prevent this kind of fraud. To improve the situation on a European level DG TAXUD published an open call in order to find a new marker that could potentially replace SY124 as Euromarker. To support DG TAXUDs policies to find a better fiscal marker, JRC has performed different kinds of tests resulting in more than 1200 samples for checking resilience of four candidate markers alongside with SY124. Generally the tests involved laundering over different adsorbents, chemical break-down and different physical treatments. All new candidate markers are colourless but road-side detection of the candidate markers is possible and based on dedicated instrumentation. Based on these experiments one candidate marker outperforms the others and is resilient to most treatments. This candidate marker could potentially be used to replace SY124.