Delaying the prayer until after the time when it is due, with no valid excuse, is a major sin. Allaah says (interpretation of the meaning):
“So woe unto those performers of Salaah (prayers) (hypocrites),
Those who delay their Salaah (prayer from their stated fixed times)”
Sa’d ibn Abi Waqqaas was asked whether delaying prayer is counted as abandoning prayer. He said, “No, but it means delaying it until after its time.”
Ibn ‘Abbaas said: “ ‘Those who delay their Salaah’ means those who delay it until after its time.”
Tafseer al-Qurtubi, 12/706.
Work is not a reason for not praying until the time for prayer is over. Allaah says (interpretation of the meaning):
“In houses (mosques) which Allaah has ordered to be raised (to be cleaned, and to be honoured), in them His Name is remembered [i.e. Adhaan, Iqaamah, Salaah (prayers), invocations, recitation of the Qur’aan]. Therein glorify Him (Allaah) in the mornings and in the afternoons or the evenings,
Men whom neither trade nor sale (business) diverts from the remembrance of Allaah (with heart and tongue) nor from performing AsSalaah (Iqaamat asSalaah) nor from giving the Zakaah. They fear a Day when hearts and eyes will be overturned (out of the horror of the torment of the Day of Resurrection)”
These men, even though they engage in trade and buy and sell, that does not distract them from remembering Allaah and establishing regular prayer and praying zakaah. Rather they make obedience and worship of Allaah their main aim and ultimate goal, and whatever comes between them and that goal, they shun it.
Based on this, you should either ask your boss to allow you enough time to pray on time, or you should leave this job which is keeping you from prayer. And whoever gives up something for the sake of Allaah, Allaah will compensate him with something better than that.
See also Question no. 34617
And Allaah knows best.