I'm a new developer. Is that referring to page 123 of the in-house documentation? Version 12.3 of the code? I have no clue.

You'd have to call it something like calculatePersonalIncomeTaxPerTaxCodeSection1_2_3, but I get exhausted just looking at that. There comes a point where the cognitive work of reading crazy long camel case names is more trouble than it's worth.

An explanation of what specification a function was written to implement is a perfectly appropriate comment. Could be improved by a direct link where possible. But it's worth noting what that comment isn't doing - specifying any implementation details. For that, I really can just read the code.