Embassy of Hungary in Washington DC published a warning: ATTENTION TO ALL FOREIGNERS PLANNING ON TRAVELING TO HUNGARY
As of 15 July, the Hungarian government applies a three-fold categorization of countries based on the coronavirus situation (green, yellow, and red), and stipulates the rules of entry of Hungarian and foreign citizens accordingly. In the case of transfer passengers, the category of the country of origin shall be applicable (for instance, in the case of passengers arriving from the United States transferring in Germany, the category of the United States has to be taken into consideration: they are regarded as passengers arriving from a country in the yellow category, and the rules of entry applicable in the case of countries in that category shall apply).
For detailed rules on entering and leaving Hungary, please visit the Liszt Ferenc National Airport’s the website: https://www.bud.hu/en/covid_19/information_on_entering_and_leaving_hungary
If you arrive from the United States and, based on the regulations detailed in the relevant government decree, you are obliged to go into home quarantine, it will be implemented after the attached form is filled in. Waiting time at the border is significantly reduced if you use the opportunity to fill in the form in advance. The form is validated on entry into Hungary by the authorities:
On the second page of the form, you’ll find the English translation of the relevant government decree.
Airlines often request additional evidence from travelers regarding their end destination. We advise our Clients that before leaving for Hungary, contact us via email for a statement that says foreigners are allowed to enter Hungary based on the regulations detailed in the relevant government decree. Please send your request, the copy of your ticket and your passport at the email@example.com address. Please give us a few days to process your request.”
Source: Embassy of Hungary in Washington DC