Answered by Ustadh Tabraze Azam
Question: If one is observing expiation fast and he forgot to make the intention at night due to tiredness and he wakes up in the morning without eating or drinking, and then he says to himself ”I’m fasting today” before mid-day, is this sufficient?
Answer: Assalamu alaikum wa rahmatullahi wa barakatuh,
I pray that you are in the best of health and faith, insha’Allah.
Your fast is valid as the default assumption is that you had the intention to continue your expiation (kaffara).
However, note that the intention for the expiatory fast needs to be clear before Fajr time. An Islamic midday (al-dahwa al-kubra) intention suffices in the current Ramadan, specifically vowed, and voluntary fasts only.
And Allah alone gives success.
Checked & Approved by Faraz Rabbani