LUXEMBOURG—European Union finance ministers tentatively agreed Friday on a set of rules and standards aimed at closing loopholes that allow wealthy multinationals to shift profits and avoid footing large tax bills.

The provisional agreement by the EU’s finance chiefs marks an important breakthrough for the 28-country bloc, which has been reeling from disclosures that multinational companies struck alleged sweetheart deals in countries such as Luxembourg that allowed them to pay very little tax in the EU.

Jeroen Dijsselbloem, the Dutch finance minister who presided over the meeting on Friday, called the agreement an “important step” in the bloc’s efforts to tackle corporate tax avoidance.

“I am confident that we have is…a good step forward in the fight against tax avoidance,” he said.

The agreement is set to be officially signed off by Monday midnight, after the finance ministers of Belgium and the Czech Republic, confirm the deal with their prime ministers—a step considered to be a formality.