My son is 20 years old now. He was 19 last year. He has a job but does not put money toward household bills. Can I still use him as a dependent?

If your son is not a full-time student, and he had over $4300 of income from working in 2021 you cannot claim him as a dependent.   He can file his own tax return to seek a refund of tax withheld from his pay and he can say that no one else can claim him ....and that is even if he is not helping with household expenses.

If he is not a full time student, over the age of 18 and has gross income of $4,300 or more in 2021 you cannot claim him as a dependent on your tax return.

To be a Qualifying Relative -

1. The person cannot be your qualifying child or the qualifying child of any other taxpayer. A child is not the qualifying child of any other taxpayer if the child's parent (or any other person for whom the child is defined as a qualifying child) is not required to file an income tax return or files an income tax return only to get a refund on income tax withheld.
2. The person either (a) must be related to you or (b) must live with you all year as a member of your household.
3. The person's gross income for the year must be less than $4,300 (social security does not count) in 2021
4. You must provide more than half of the person's total support for the year.
5. The person must be a U.S. citizen or a U.S., Canada, or Mexico resident for some part of the year.
6. The person must not file a joint return with their spouse.