@Kipmc7 @BrailMethod - please review the structure of the form 1040. Look at the section headings in the left margin that take up the first inch or so on a piece of paper.
1) Taxable Income is all reported and calculated on lines 1-15.
2) INCOME TAX and the NON-REFUNDABLE CREDITS is netted out on Line 22 (there are other taxes such as Self Employment and any 10% penalties related to IRA, etc. that get added on Line 23, so that Line 24 is TOTAL TAX.) As pointed out by others, Line 22 can not go below zero; that is what makes the credits 'non-refundable: there is no refund available because Line 22 is not permitted to go below zero!/
3) The next section is PAYMENTS which include W-2 withholdings, and estimated tax payments PLUS REFUNDABLE CREDITS (mostly addition CTC, EITC and AOTC credits).
Once section 3) is subtracted from Section 2) the IRS determines whether the taxpayer owes money or gets a refund.
My point is where folks get confused is that the tax and the non-refundable credits all get calculated WELL before we begin talking about withholdings from W-2s and estimated tax payments.
