Is a son sinful if he gives his parents a large portion of his salary and keeps a small amount for himself without informing them of the full salary, knowing that he lives under their care and needs the remaining amount for his personal needs?

What you do by honoring your parents is commendable, and there is no harm in giving them your salary, except for what you exclude for yourself. If telling them the truth would anger them or cause discord, then there is no blame upon you for concealing it and using allusions (ma'areed) instead of outright lying. And if lying becomes necessary in this situation, there is no harm upon you, because verified scholars consider it permissible in anything that involves a benefit without harming others. Indeed, Ibn al-Jawzi and Ibn al-Qayyim stated the permissibility of lying for a commendable purpose that cannot be achieved except through it.