Historically, authorities have always required an IE599 message.
Nevertheless, in the judgment of 28 March 2019 ( case C-275/18 ), the CJEU pointed out that in the context of applying the 0% rate, the condition of actual exit of the goods from the territory of the Union is important. However, it is not necessary for the goods to be placed under the export customs procedure.
After this judgment, the authorities liberalized their approach.
Source: zrozumvat.pl