A person wakes on an ordinary day and decides for the first time, “I will use today to make up a Ramadan fast.” No intention for qada existed overnight.
The missed Ramadan duty is not discharged by the newly formed morning intention. Whether the day can be a voluntary fast depends on its separate conditions, but it is not counted as qada.
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Kitab al-Sawm: Categories of Fasting and Rules of Intention
A person wakes on an ordinary day and decides for the first time, “I will use today to make up a Ramadan fast.” No intention for qada existed overnight.
The missed Ramadan duty is not discharged by the newly formed morning intention. Whether the day can be a voluntary fast depends on its separate conditions, but it is not counted as qada.