I have changed the way I add date tags to my PKM notes. It used to be in the form of #2021- #2021-02-26. This as my main viewer on these notes, Obsidian, only supports search on full tag names, so searching on #2021- does not surface #2021-02 as tag. In December Obsidian introduced nested tags, which you can do by adding a / in between, like in #maintag/subtag/subsubtag etc. Normally I am adverse to sorting tags into hierarchies, tags are not categories after all. But for dates a nested hierarchy is useful: now I can add #2021/02/26 as tag, but in search that will return results for #2021/ and for #2021/02 too. It took a bit of time, but I’ve now replaced all my old date related tags with the new nested tags. An added benefit is that it cleans up my taglist enormously, as all tags related to a year are collapsed into one.