A more thorough explanation:

The assignment-of-income doctrine is a legal principle in family law that states that the person who earns income is the one who is taxed on it, regardless of who receives the money. This means that if someone assigns their future income to another person, the assignor is still responsible for paying taxes on that income.

For example, in the case of Lucas v. Earl, a husband who was the sole wage-earner tried to assign half of his income to his wife and only pay taxes on the remaining half. However, the court ruled that this was not allowed under the assignment-of-income doctrine, and the husband was required to pay taxes on all of his income.

Another example could be a business owner who tries to assign their income to a family member or friend to avoid paying taxes. This would also be prohibited under the assignment-of-income doctrine, and the business owner would still be responsible for paying taxes on their earnings.

Overall, the assignment-of-income doctrine ensures that individuals cannot avoid paying taxes by assigning their income to someone else. It is an important principle in family law and helps to ensure fairness in the taxation system.