923. Washing on Yom Kippur

133:3 The prohibition against bathing is discussed above, in 124:7-9.  On Yom Kippur, one is not only forbidden to wash for enjoyment, he may not wash any more than is necessary. If one was in shul praying all day, then he need not wash his hands for the Ne’ilah, mincha and maariv services.

133:4 The kohanim who go up to bless the congregation must have their hands washed up to the wrist. If they did not wash their hands in the morning – just their fingers, albeit with the bracha – then, since that washing is not sufficient for blessing the congregation and they now wash up to the wrist, then they must recite the bracha for hand-washing a second time. It would be preferable for them to wash their hands in the morning up to the wrist so that they will not need to recite the bracha a second time. (Refer to Mishnah Brurah 128:24 for more on this topic.)