For kabuki actors, up to roughly what year does a work count as "classical"?

You may expect an answer of the form "up to the year such-and-such," but no such line exists. Or rather: the word "classical" points less to a period than to a difference in how a work is transmitted.

Works from Edo through Meiji accumulated kata across repeated stagings: who played it and how, where the pause falls, which house transmits which form — layer upon layer wound around the work. To stage one is to inherit those layers. Shin-kabuki, born from late Meiji, was written as dramatic literature by writers such as Tsubouchi Shōyō, and begins from a fixed text. The order is reversed: the actor interprets what is written rather than building the form. The difference is substantial.

In practice the field works with three layers — classics, shin-kabuki, new works — but where the border cases fall varies from speaker to speaker, and there is no strict consensus. A Meiji-period work that has since been staged long enough for its kata to settle may be treated as classical in effect. The longer a new work lasts, the closer it moves to the classics. "Classical" is better understood as a moving boundary than as a fixed range.