Is the capital gains tax rate bracket calculated after deductions?

Question

For example, if someone (single filer) makes 45k in regular income and wants to sell stock which would realize 5k of long-term capital gains:

Do they pay 15% on the capital gains because, with 50k total income, they are in the 15% capital gains bracket?

Or, do they pay 0% on the capital gains because, with 50k total income minus the 12k standard deduction (38k), they are in the 0% capital gains bracket?

This question is similarly about deductions and capital gains, but doesn't answer about when the bracket changes.

Answer 1

From Tax Topic 409: (emphasis added)

The tax rate on most net capital gain is no higher than 15% for most taxpayers. Some or all net capital gain may be taxed at 0% if you're in the 10% or 12% ordinary income tax brackets. However, a 20% tax rate on net capital gain applies to the extent that a taxpayer's taxable income exceeds the thresholds set for the 37% ordinary tax rate ($425,800 for single; $479,000 for married filing jointly or qualifying widow(er); $452,400 for head of household, and $239,500 for married filing separately.

So the capital gain tax brackets are based on the taxable income brackets (meaning after all income and deductions, but before credits).