Although one way of specifying the Schengen Zone time limit is 3 months it is actually 90 days. Do not get caught overstaying. 1 July to 30 September may be 3 months but to Schengen it is 92 days. Partial days count as full days. Watch out for midnight landings and departures; you and Schengen can easily come up with a different count this way. If you have spent any time in the Schengen Zone in the past 180 days subtract the days from that stay from the 90 days to find the number of days you can spend this time.
See:
As for one way tickets:
Countries fine airlines that send over visitors that the governments will not allow in and the airlines also have to send them back at their own cost. So the airlines use their International Air Transport Association to keep track of the entry requirements. IATA publishes the information as a book called Travel Information Manual (TIM) and they also have it computerized as Travel Information Manual Automatic (TIMATIC.)
TIMATIC can be accessed via the web url
https://www.iatatravelcentre.com but the following site provides a somewhat easier interface (but likely not as good for general use):
https://www.united.com/web/en-US/apps/vendors/default.aspx?i=TIMATIC
See also:
The English language version of the EU's Schengen Borders Code can be found at:
REGULATION (EU) 2016/399 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL
of 9 March 2016 on a Union Code on the rules governing the movement of persons across borders (Schengen Borders Code)
Article 6 is the section for "Entry conditions for third-country nationals" and it does not require a return ticket to enter the Schengen Area. Paragraph 1(c) does state though:
they justify the purpose and conditions of the intended stay, and they have sufficient means of subsistence, both for the duration of the intended stay and for the return to their country of origin or transit to a third country into which they are certain to be admitted, or are in a position to acquire such means lawfully;
IATA checks whether you are allowed to fly and has access to a database to determine that. That is because Annex V, Part A, Paragraph 2 of the Schengen Borders Code mentions that a carrier has to transport someone that is refused entry into the zone.
2. If a third-country national who has been refused entry is brought to the border by a carrier, the authority responsible locally shall:
(a) order the carrier to take charge of the third-country national and transport him or her without delay to the third country from which he or she was brought, to the third country which issued the document authorising him or her to cross the border, or to any other third country where he or she is guaranteed admittance, or to find means of onward transportation in accordance with Article 26 of the Schengen Convention and Council Directive 2001/51/EC (1);
For other versions and languages for the Schengen Borders Code see:
