Would it be proper to make the intention for qadha fast at the time of sehri if one has not made niyat at night?

Question:

Would it be proper to make the niyat for qaza fast at the time of sehri if one has not made niyat at night.

Answer:

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.

Niyah (intention) for the Qadha' should be made from the night. This means that this niyah can be made any time between Sunset and Subah Sadiq. 

Hence niyah at the time of Sahur (which is before Subh Sadiq) will be fine, and the qadha' will be proper. [i]

And Allah Ta’āla Knows Best

Mufti Faisal bin Abdul Hameed al-Mahmudi
www.fatwa.ca 

[i]

درر الحكام شرح غرر الأحكام (1/ 198)

(قوله والمراد النية من الليل) أقول الشرط عدم تأخيرها عن طلوع الفجر فتصح مقارنة لطلوعه ومن فروع لزوم التبييت في غير المعين لو نوى القضاء من النهار فلم يصح هذا هل يقع نفلا في فتاوى النسفي نعم، ولو أفطر يلزمه القضاء