Crimean authorities say all goods brought to the peninsula from the Ukrainian mainland are now subject to customs declaration and duties.
Following Crimea's annexation by Russia in March, the Russian authorities declared a "transition period" during which goods from the Ukrainian mainland could travel freely into the peninsula. That period ended on January 1.
The region's customs service said in a statement that all imports from Ukraine must now be declared "in writing or electronic forms using the customs declaration and paying customs duties" into the Russian budget.
There are concerns the new customs duties will further raise prices in Crimea.
Crimea unified with Russia in March following a local referendum condemned by Kyiv, the United States, the EU, and others around the world as illegal.