In accordance with Article 9 "Conditions for the validity of travel documents" of the International Passenger Service Agreement  (IPSA), 

The validity of tickets is 2 months. 

Carriers may shorten or extend their validity through bilateral or multilateral agreements. 

The validity period of tickets starts: 

- in the absence of a reserved seat or a puncher mark (a stamp) - 

on the day specified by a passenger and indicated on a ticket by a contractual carrier (a point of sale). The period between the day the ticket is issued and the day its validity starts cannot exceed the term for the preliminary sale of travel documents established by the carrier; 

- if there is a reserved seat or a puncher mark (a stamp) on a ticket - on the day of departure of the passenger. 

The validity period of tickets ends: 

- in the absence of a reserved seat or a puncher mark (a stamp) - 

at 12 a.m. on the last day of the validity of the ticket established at the applicable tariff or defined by bilateral or multilateral agreements; 

- if there is a reserved seat or a puncher mark (a stamp) in accordance with the specified information on the date and time of arrival of the passenger at the destination. 

The validity of a travel document shall be extended in the following cases: 

1) for the time of delay in carriage, if the specified delay occurred due to the fault of participants in the carriage process; 

2) if a passenger is not provided with a seat on the train - for the entire time until the departure of the next train, in which the passenger will be provided with a seat; 

3) upon interruption of a trip, in accordance with Article 13 of this Agreement. 

If, for a forced reason, a passenger is not able to finish the trip within the set validity period of the ticket, then he/she is granted the right, before the expiration of the validity period, subject to the submission of the relevant documents, to contact the carrier with a request to extend the validity of the ticket. 

The validity of a ticket can be extended at most two times, and the term of each extension shall not exceed two months. 

The carrier requested by the passenger to extend the validity of the ticket, who recognizes, that the reasons for the need for extension is valid, shall extend the validity of the ticket. Clause 4. A travel document shall be considered invalid for travel if the information contained in it in accordance with Article 7 Clause 2 and Article 8 Clause 1 of this Agreement is illegible or contains corrections and marks not provided for by this Agreement. Clause 5. Travel documents (a ticket and a reserved seat issued on the same form), which contain information about the date and time of departure and arrival of a passenger, shall be valid for the train or car in which the passenger travels to the destination.