Reservation

A reservation is one unit at one property, inside a booking. Each has its own RS-… ID, status, guests, price and policies.

Call	Purpose
`GET /v2/bookings/{booking_id}/reservations/{reservation_id}`	Retrieve one reservation
`POST /v2/bookings/{booking_id}/reservations/{reservation_id}/modification-offers`	Get offers for changing a reservation's dates
`PUT /v2/bookings/{booking_id}/reservations/{reservation_id}`	Apply a modification offer
`DELETE /v2/bookings/{booking_id}/reservations/{reservation_id}`	Cancel (Cancellation)

Changing dates (modification)

A modification is a two-step flow, done per reservation.

1. Ask for modification offers

POST /v2/bookings/BK-BQLPC7ZB/reservations/RS-Y6MXARWD/modification-offers
{ "check_in": "2026-08-05", "check_out": "2026-08-08" }

The response contains the offers for the new dates. Each has an id, price and rate_plan with the new policies.

Same unit and rate: the modified reservation keeps the same unit type and rate plan. Only the dates and price change.
Empty list: there is no availability for the new dates.

The request can be rejected with 422 when the reservation can't be modified:

The stay has already started.
The rate is non-refundable.
The hotel's system doesn't support modifications.
The dates are unchanged.

2. Apply the modification

PUT /v2/bookings/BK-BQLPC7ZB/reservations/RS-Y6MXARWD
{
  "offer_id": "fb2bc6ee-423a-4281-947b-07b8c09ff5b6",
  "payment": { "type": "visa", "card_number": "4111111111111111", "cvv": "123",
               "card_holder": "John Doe", "expiry_month": "11", "expiry_year": "2028" }
}

payment is required. Send full card details including CVV. It doesn't have to be the card used for the original booking.
Response: the updated reservation, with its new dates and price.
Offers are tied to their reservation. A modification offer can only be applied to the reservation it was requested for. To change dates for a multi-unit booking, request offers for each reservation separately.

Error	Meaning
400 `Invalid Body provided`	Malformed JSON, or a field has the wrong type (all payment fields are strings)
400 with validation messages	Missing `offer_id` or `payment`, invalid card expiry, etc.
404 `Modification offer could not be found`	Offer expired or belongs to another reservation; request new modification offers
404 `Not found`	Unknown booking or reservation

Guests

guests on a reservation are the people staying in that unit.

Send at least one guest per reservation.
Send no more guests than the adults + children you searched for in that unit.
First and last name are required. All other guest fields are optional.

See Booking → Customer and guest data for formats and per-hotel limits.