CFR 20 is related to Social Security, which is why your link is from ssa.gov. CFR 26 is income tax, and the part relevant to the AOTC. The cites I’ve been providing are all under CFR 26.
I don’t disagree that you could find yourself in a situation where he is not your dependent but is still not eligible for the refundable AOTC.
@allyphoe Thanks - found CFR 26 Section 119 with specific wording with respect to universities
“(d) Lodging furnished by certain educational institutions to employees
(1) In general
In the case of an employee of an educational institution, gross income shall not include the value of qualified campus lodging furnished to such employee during the taxable year.”
(https://www.law.cornell.edu/uscode/text/26/119)
@mommdc I would have to do the math to see if would be worthwhile to take a loan. He may qualify to file as non-dependent. But he may not be eligible for any refundable tuition tax credit, because of the restrictions from IRS on who can qualify for refundable tax credit. I started out this thread thinking some $1000 in refundable credit was possible for TY 2019 . Now it looks like $0 is more likely 
But you won’t know how much he will earn yet in 2019.
Is the room and board that is provided to an RA, being provided for the convenience of the employer, or is it being provided as compensation for services? Does the RA receive any stipend or other compensation beyond room and board? If not, if they are serving as RA only in exchange for the room and board, then I would think that the room and board is compensation and not a benefit being provided for the convenience of the employer…
Because it’s not included in gross income (meaning, it’s not subject to tax) does not mean that it is not earned income, under the definition of that term that is used to determine eligibility for the refunded part of the AOTC.
The fact that it’s excluded under 119 does, however, mean that it’s not earned income, per Reg Sec 1.911-3©(1) (quoted above).
So a simple question
Option 1 - Claim your child as a dependent (get $1000 child tax credit). If you are in the higher brackets, this is worth about $600
Option 2 - Do a lot of paperwork to get $1000 in earned income tax back
Is this what we are discussing?
Option 1 has a maximum payout of $500 under current law
Option 2 is a $1,000 refundable tax credit for a kid who has no income tax liability
Option 3 is that the kid is neither a dependent nor eligible for the refundable AOTC.
You don’t get to choose between those options. You have to figure out which one you’re eligible for, where each is mutually exclusive.
@mommdc wrote: “But you won’t know how much he will earn yet in 2019.”
He has a summer internship and knows how much he’ll make. His only other job is the RA position during the rest of the year. He gets room and board for that but no stipend of any sort.
@“suhel d” When I started the thread, those were what I thought were my options. But now it looks like DS1 may not be a dependent (due to worksheet for calculating support) but doesn’t have enough earned income for Option 2 .
IRC sect. 119 excludes from gross income “Meals and lodging furnished to employee, his spouse, and his dependents, pursuant to employment.” Being excluded from gross income does not mean that it is therefore not earned income. Reg. sect. 1.911-3(c) says, however, that such an amount is not included in foreign earned income. I am not aware that OP’s son’s RA benefits are an element of foreign earned income.
You are aware that Sec 911, which is the section you quoted as defining earned income, is the section governing the foreign earned income exclusion, and that the incorporation by reference in IRC 1(g) means that earned income is the same for Kiddie Tax, the refundable AOTC, and the FEIE? And that a Reg Sec that starts with 1.911 means that they’re the regs pertaining to IRC 911?
Part 1
Yes, I am aware of all that.
The question here is whether or not OP’s son has the earned income required to qualify for a refunded portion of the
AOTC.
Let’s takes this step-by-step, from the beginning.
Section 25A of the Internal Revenue Code (IRC) covers the American Opportunity Tax Credit (AOTC) and the Lifetime Learning Credit.
https://www.law.cornell.edu/uscode/text/26/25A
Subsection (i) PORTION OF AMERICAN OPPORTUNITY TAX CREDIT MADE REFUNDABLE states in whole:
Forty percent of so much of the credit allowed under subsection (a) as is attributable to the American Opportunity Tax Credit (determined after application of subsection (d) and without regard to this paragraph [1] and section 26(a)) shall be treated as a credit allowable under subpart C (and not allowed under subsection (a)). The preceding sentence shall not apply to any taxpayer for any taxable year if such taxpayer is a child to whom subsection (g) of section 1 applies for such taxable year.
So we know that the refundable part of the AOTC is not available if subsection (g) of IRC section 1 applies to the taxpayer claiming the credit and that taxpayer is a child. Paragraph (2) of subsection (g) tells us if the subsection applies:
I CHILD TO WHOM SUBSECTION APPLIES This subsection shall apply to any child for any taxable year if—
(A) such child—
(i) has not attained age 18 before the close of the taxable year, or
(ii)
(I) has attained age 18 before the close of the taxable year and meets the age requirements of section 152(c)(3)
(determined without regard to subparagraph (B) thereof), and
(II) whose earned income (as defined in section 911(d)(2)) for such taxable year does not exceed one-half of the
amount of the individual’s support (within the meaning of section 152(c)(1)(D) after the application of section
152(f)(5) (without regard to subparagraph (A) thereof)) for such taxable year,
(B) either parent of such child is alive at the close of the taxable year, and
(C) such child does not file a joint return for the taxable year.*
https://www.law.cornell.edu/uscode/text/26/1
Continued…
Part 2
I’ll assume that OP’s son was 18 years old before the close of the taxable year, had a parent who was alive at the end of the tax year, and is not filing a joint return for the taxable year. The question becomes one of the taxpayer’s amount of earned income in relation to the amount of the taxpayer’s support, and the statute refers to IRC section 911(d)(2) for the definition of the term “earned income.”
Section 911 is titled “Citizens or residents of the United States living abroad.” We’ve been referred here not necessarily because the taxpayer who wants to claim the refundable part of the AOTC lives abroad or has foreign earned income, but simply because paragraph (d)(2) of the section already conveniently provides a useful definition of the term “earned income” for purposes of the AOTC refundable credit.
https://www.law.cornell.edu/uscode/text/26/911
911(d)(2) states in whole:
I EARNED INCOME
(A) In general
The term “earned income” means wages, salaries, or professional fees, and other amounts received as
compensation for personal services actually rendered, but does not include that part of the compensation derived by
the taxpayer for personal services rendered by him to a corporation which represents a distribution of earnings or
profits rather than a reasonable allowance as compensation for the personal services actually rendered.
(B) Taxpayer engaged in trade or business
In the case of a taxpayer engaged in a trade or business in which both personal services and capital are material
income-producing factors, under regulations prescribed by the Secretary, a reasonable allowance as compensation
for the personal services rendered by the taxpayer, not in excess of 30 percent of his share of the net profits of such
trade or business, shall be considered as earned income.*
In my opinion, the in-kind benefits received by OP’s son as an RA qualify as “other amounts received as compensation for personal services actually rendered,” and therefore these benefits are earned income. The fact that the school assigns a monetary amount to these benefits supports this opinion.
In-kind benefits of room and board that are received by an RA are earned income but are not included in gross income and as such are not taxable. This is covered in IRC section 119, “Meals or lodging furnished for the convenience of the employer,” which is included in IRC Part III, “Items specifically excluded from gross income.”
https://www.law.cornell.edu/uscode/text/26/119
Section 119 states in part:
I MEALS AND LODGING FURNISHED TO EMPLOYEE, HIS SPOUSE, AND HIS DEPENDENTS, PURSUANT TO EMPLOYMENT There shall be excluded from gross income of an employee the value of any meals or lodging furnished to him, his spouse, or any of his dependents by or on behalf of his employer for the convenience of the employer, but only if—
(1) in the case of meals, the meals are furnished on the business premises of the employer, or
(2) in the case of lodging, the employee is required to accept such lodging on the business premises of his employer
as a condition of his employment.*
and…
I LODGING FURNISHED BY CERTAIN EDUCATIONAL INSTITUTIONS TO EMPLOYEES
(1) IN GENERAL
In the case of an employee of an educational institution, gross income shall not include the value of qualified campus
lodging furnished to such employee during the taxable year.*
Internal Revenue Regulation 1.911-3(c)(1), cited previously in this thread, excludes from earned income any income that is excluded from gross income under section 119, but only if the income was foreign earned.
https://www.law.cornell.edu/cfr/text/26/1.911-3
*1.911-3 Determination of amount of foreign earned income to be excluded.
(a)Definition of foreign earned income. For purposes of section 911 and the regulations thereunder, the term “foreign earned income” means earned income (as defined in paragraph (b) of this section) from sources within a foreign country (as defined in § 1.911-2(h)) that is earned during a period for which the individual qualifies under § 1.911-2(a) to make an election. Earned income is from sources within a foreign country if it is attributable to services performed by an individual in a foreign country or countries. The place of receipt of earned income is immaterial in determining whether earned income is attributable to services performed in a foreign country or countries.
(b)Definition of earned income -
(1)In general. The term “earned income” means wages, salaries, professional fees, and other amounts received as
compensation for personal services actually rendered including the fair market value of all remuneration paid in any
medium other than cash. Earned income does not include any portion of an amount paid by a corporation which
represents a distribution of earnings and profits rather than a reasonable allowance as compensation for personal
services actually rendered to the corporation.
(2)Earned income from business in which capital is material. In the case of an individual engaged in a trade or
business (other than in corporate form) in which both personal services and capital are material income producing
factors, a reasonable allowance as compensation for the personal services actually rendered by the individual shall
be considered earned income, but the total amount which shall be treated as the earned income of the individual
from such trade or business shall in no case exceed thirty percent of the individual’s share of the net profits of such
trade or business.
(3)Professional fees.Earned income includes all fees received by an individual engaged in a professional occupation
(such as doctor or lawyer) in the performance of professional activities. Professional fees constitute earned income
even though the individual employs assistants to perform part or all of the services, provided the patients or clients
are those of the individual and look to the individual as the person responsible for the services rendered.
(c)Amounts not included in foreign earned income. Foreign earned income does not include an amount:
(1) Excluded from gross income under section 119*
…
I believe this is the crux of the misunderstanding. The definition of “earned income” that the AOTC uses to determine eligibility for the refundable portion of the credit comes from the part of the IRC that deals with income from sources outside the United States. But unless the taxpayer actually has foreign source income, the definition of “earned income” as spelled out in IRC section 911(d)(2) is all that is necessary to determine whether or not the taxpayer has sufficient earned income to qualify for the refundable part of the AOTC.
Just to be clear, I am only offering my opinions, and none of what I am offering is tax and/or legal advice. And I apologize in advance if your eyes glazed over after the first paragraph.
I think we’re going to have to agree to disagree here. In my opinion, you’re misconstruing the interaction of the subsections of 1.911-3.
But I don’t think anyone but us cares at the moment, and we aren’t having any luck convincing one another. 
Hey, I’m always willing to learn. If you think I’m misconstruing the interaction of the subsections of 1.911-3, why don’t you shoot me a PM and explain why parts of the IRS statutes and regulations dealing with foreign earned income, other than the simple definition provided in 911(d)(2), have anything to do with determining earned income for a taxpayer who has no foreign income.
Please don’t make it private, I would like to read this answer.