The European Commission (EC) has proposed that Italy and Spain align their taxation of ports with state aid rules.
In Italy, ports are fully exempt from corporate income tax, while in Spain, they are exempt from corporate income tax on their main sources of revenue, such as port fees or income from rental or concession contracts.
The EC said this can provide them with a competitive advantage in the internal market.
In April 2018, it informed their governments of its concerns.
It has now "invited" both to adapt legislation from 1 January, 2020, to ensure corporate tax will be paid in the same way as other companies do.
Each country now has two months to react.
