Cross-border sales, purchases and transit

If you buy and resell commodities or other goods that switch possession of ownership in Croatia or are transited through Croatia including import and export operations, you may need to register for VAT, file monthly VAT returns, EU sales lists, EU acquisition lists, and other documentation, and issue invoices under Croatian rules.

Registration triggers include:

Acquiring goods from another EU country that are transported to Croatia, potentially exempt if sold immediately to a Croatian business (triangulation exemption).
Selling goods to buyers from another EU country or outside the EU that are transported outside Croatia.
Acquiring and selling goods within Croatia, if resold to individuals within Croatia. Registration is not required if you only buy from and sell to Croatian businesses, but companies often register to be more flexible for intra-EU opportunities and to reclaim VAT by offsetting it with VAT liability in the same month, avoiding lengthy refund processes.
Importing from outside the EU followed by sales to another EU country.

Various other situations may trigger registration. You should assess your case individually.