If a person one day did not put on Tefillin, and he remembers or has the opportunity to do so only after the sun had set, may he still put on his Tefillin (despite the fact that Tefillin are never worn at nighttime)?
Halacha allows a person in such a case to put on Tefillin throughout the period of "Bein Ha'shemashot," or twilight, which extends for 13.5 minutes, or, according to some authorities, for 17-18 minutes, after sundown. One who puts on Tefillin during this period may even recite a Beracha. Therefore, if a person was sick, Heaven forbid, or away on a trip, and could not wear Tefillin before sundown, he must put his Tefillin on with a Beracha so long as 18 minutes have not passed since sundown.
A similar question arises as to whether one may put his Tefillin on after reciting Arbit. Occasionally, particularly in the summer months when the sun sets very late in the evening, people recite Arbit before sunset (after the point of "Pelag Ha'mincha"). In a certain sense, a person who recites Arbit establishes that for purposes of Halacha, night has already fallen. Perhaps, then, after reciting Arbit one would be unable to put on his Tefillin, even before the sun sets.
The Shulchan Aruch indeed rules that one may not put Tefillin on after Arbit, even if one had not worn them at all the entire day and the sun has yet to set. As the Mishna Berura (commentary on the Shulchan Aruch by the "Chafetz Chayim," Rabbi Yisrael Meir Kagan, Poland, 1839-1933) mentions, however, many authorities dispute this ruling of the Shulchan Aruch. In their view, a person who, for whatever reason, had not worn Tefillin the entire day must wear them even if he had already recited Arbit, unless the aforementioned period of "Bein Ha'shemashot" has passed. Halacha follows this second opinion, requiring one to wear Tefillin after reciting Arbit if he hadn’t earlier in the day. However, given the debate on the matter, in such a situation one would not recite a Beracha.
It should be emphasized that we speak here only of one who did not wear Tefillin at all the entire day. If a person did wear Tefillin during the day and wishes to wear them again after he recited Arbit, he should not do so.
One who follows the custom to wear Tefillin Rabbenu Tam, and one day did not put them on until after he recited Arbit, may put them on even after Arbit, so long as "Bein Ha'shemashot" has not passed. Of course, one never recites a Beracha when placing Tefillin Rabbenu Tam, so it goes without saying that in such a case one would not recite the Beracha.
Summary: If a person did not wear Tefillin at all the entire day, he must still wear them – with a Beracha – so long as 18 minutes have not passed since sunset. This applies even if he already recited Arbit, though in such a case one does not recite a Beracha over the Tefillin. Similarly, one who did not wear Tefillin Rabbenu Tam one day, as he normally does, may put them on – though obviously without a Beracha – even after Arbit, until 18 minutes after sunset.
