Unless your state is exempt from Reg. Z or your state requirement is more stringent, Reg. Z will prevail.
Unless your state is exempt from Reg. Z - some states have their own version of TIL and are "excused" from Reg. Z.
state requirement is more stringent - if state law is more stringent than Federal Law - state law will prevail - unless you operate under the preemption rules.
Reg. Z will prevail - if neither of the above applies then Reg. Z prevails.
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The opinions expressed are mine and they are not to be taken as legal advice.