When do laws take effect?

Article 2 of the New Civil Code. Laws shall take effect after fifteen days following the completion of their publication in the Official Gazette, unless it is otherwise provided. This Code shall take effect one year after such publication.

TaƱada v. Tuvera (1986):

[1] The clause "unless it is otherwise provided" refers to the date of effectivity and not to the requirement of publication itself, which cannot in any event be omitted.
[2] Publication is indispensable in every case, but the legislature may in its discretion provide that the usual fifteen-day period shall be shortened or extended.
[3] EXCEPTION: Interpretative regulations and those internal in nature need not be published.