*Ahkaam-e-Ramzan-ul-Mubarak*
Things that invalidate the fast:
(1) Putting medicine in the ear or nose, (2) Vomiting intentionally with a full mouth, (3) Water going down the throat while rinsing the mouth, (4) Ejaculation due to touching a woman, etc., (5) Swallowing something that is not normally eaten, such as wood, iron, raw wheat grain, etc., (6) Intentionally sending the smoke of loban or oud, etc., into the nose or throat; smoking bidis, cigarettes, and hookahs are included in this ruling, (7) Eating or drinking forgetfully and then thinking that the fast would have been broken by it, then intentionally eating or drinking, (8) Eating Sehri after Subh-e-Sadiq (true dawn) thinking it was night, (9) The day was remaining; but mistakenly thinking that the sun had set, breaking the fast.
Note: The fast is invalidated by all these things, but only Qaza (making up the fast) is obligatory, Kaffarah (expiation) is not necessary.
(10) The fast is invalidated by knowingly having intercourse with one's wife or eating and drinking, and both Qaza and Kaffarah are obligatory.
The Kaffarah is to free a slave.
Otherwise, keep sixty consecutive fasts, without interruption, otherwise, you will have to complete sixty fasts from the beginning, and if there is no strength for fasting either,
Feed sixty poor people two meals a day to their fill.
Nowadays, Shari'a-compliant slaves or maids are not found anywhere; therefore, the last two options are definite.
Wallahu A'lam Bis-Sawab