For the individual, repentance is accepted right up until the death rattle (gharghara) reaches the throat — "Allah accepts the repentance of His slave as long as he has not yet begun to die." Universally, the door of tawbah closes only when the sun rises from the west, one of the major signs of the Hour, after which a disbeliever's faith and a sinner's repentance are no longer accepted. Until one of these two moments arrives, no sin is ever too great to bring back to Allah.
Evidence — the daleel
Jami al-Tirmidhi 3537Sahih Muslim 2703 Ṣaḥīḥ
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.