The eurozone's biggest banks will face an annual bill of up to 15 million euros ($20 million) apiece for being supervised by the European Central Bank, the ECB said on Tuesday. The ECB said in a statement that the costs incurred in its new role as Europe's sole banking supervisory -- which it takes over in November -- are expected to amount to 260 million euros in 2015. As part of the new Single Supervisory Mechanism (SSM), the ECB will directly supervise up to 130 institutions classified as "significant" with assets in excess of 30 billion euros. Smaller, less significant banks will remain under the remit of the national supervisory authorities. Of the overall sum of 260 million euros, staff costs would amount to around 60 percent for staff costs, premise-related costs to 10 percent and the remaining 30 percent would be accounted for by other operating expenditure such as travel, consultancy and IT services, the ECB said. While the ECB said that the precise costs can only be confirmed in 2015, "a preliminary analysis has shown that for 2015 the annual fee for a directly supervised bank may range from 150,000 euros to 15 million euros." However, most of the directly supervised banks would pay between 700,000 euros and 2.0 million euros, the ECB calculated. Similarly, around 75 percent of the smaller, indirectly supervised banks may pay between 2,000-7,000 euros per years, while the bigger banks in this category could faced a bill of abount 200,000 euros. The annual fee would be payable on July 1. The ECB said it would conduct a review of the cost framework and the methodology for calculating it in 2017.