Russia’s finance ministry said on Monday Moscow may offer a special tax regime for Ukraine’s southern Crimea region, which voted overwhelmingly in a referendum on Sunday to join Russia.

“Undoubtedly, the probable accession of Crimea to Russia will have a very serious impact,” Deputy Finance Minister Sergei Shatalov told a local business conference.

“I do not rule out a special tax regime (during Crimea’s transition period),” he added, without giving any further details.