Standard and Plus have a seven-day cutoff
Eurostar’s UK help centre says Standard and Plus tickets may be refunded up to seven days before departure, with a £25, €25 or $40 fee per leg and passenger depending on the booking currency. This is not a flat charge for an entire family itinerary. Eurostar SNAP tickets are separately described as non-refundable and non-exchangeable. Fares issued by an external agent should be checked with the original booking channel because the online refund controls may differ.
There is no single Eurostar cancellation deadline for every ticket. Look up your booking’s travel class and the conditions shown in Manage your Booking before requesting money back or moving the train to a new time.
Premier has a different deadline
Eurostar Premier tickets are refundable without a fee until 48 hours after the originally booked departure time under the current policy; more than 48 hours after departure they are non-refundable. Eurostar lists a service charge for requests made by phone or at the station. If you intend to change rather than cancel, Standard and Plus allow a date or time exchange under their own deadline and fare-difference rules; a change made close to departure can alter later refund eligibility.
Work from the original ticket conditions
Open Manage your Booking to view the terms that apply to that particular fare, including any connection, package or promotional exception. Keep the booking reference, payment record and the confirmation of any requested refund. If Eurostar itself cancels the train, do not assume the change-of-mind fee table determines the response to a disrupted service; use its disruption and assistance information for that event.
How this plays out
Two travellers bought Standard tickets for the same return journey. If both cancel both legs within the eligible window, the fee can be charged per person and leg; they should check the on-screen refundable balance rather than subtracting one £25 fee from the total booking.
Eurostar’s refund FAQ and fare-class conditions give the current direct-booking distinctions.