According to Madhhab:
If a person traveled in Ramadhan from a country which has 30 days Ramadhan to a country which has 29 days. And he didn’t fast one day in which he was travelling, does he have to keep Qadha of that fast? He has already fasted 29 days and the country which he’s doing Eid in also has 29 days. The eid is on the same day in both countries because the country with 30 days Ramadhan started one day earlier.
From the manner in which your query has been posed we understand that the person undertook a journey on the day that Ramadaan commenced in his country, but didn’t fast on the first day of Ramadaan due to being a Musaafir.
If this is the case, then yes, the person will have to keep Qadha of the missed fast after the month of Ramadaan since fasting was already obligatory upon him in his country.
And Allah Ta’aala knows best!
ANSWERED BY: Mufti Mohammed Desai
CHECKED AND APPROVED BY: Mufti Muhammed Saeed Motara Saheb D.B
Date: 04 Jumadal Ukhra 1441
English Date: 30 January 2020