What is the ruling on deception and lying at work to escape punishment or delay, and is 80% of earned lawful income considered good?

The hardship of work does not permit lying, deception, or betrayal, for the Prophet, peace and blessings be upon him, said: "Whoever cheats is not from me," and "Deceit and treachery are in the Hellfire." Likewise, there are prohibitions against false speech and action.

If you are able to perform the work properly, then continue with it. If you need a break, seek permission from your supervisor. It is not permissible to deceive him with lies.

Your intention for a part of your salary to be lawful does not justify this for you, as the ill effects of the unlawful are serious.

Lawful means of earning are many. Whoever fears Allah, He will make his matters easy for him and provide for him, for Allah Almighty says: "And whoever fears Allah - He will make for him a way out And will provide for him from where he does not expect" (Quran 65:2-3), and His saying: "And whoever fears Allah - He will make for him ease in his matter" (Quran 65:4), and His saying: "Indeed, Allah is with those who fear Him and those who are doers of good" (Quran 16:128).

The Prophet, peace and blessings be upon him, said: "Indeed, the Holy Spirit breathed into my heart that no soul will die until it completes its term and fully receives its sustenance. So fear Allah and be graceful in seeking provision."