When is it necessary to delay the start of Shemoneh Esrei?

A person must respond to Kedusha, Borchu and Amen Y’hei Shmei Rabba during Kaddish at least once a day, and it is forbidden to put himself in a position in which he will not be able to answer. Therefore, if a person walks into shul after the tzibur has already begun Shemoneh Esrei and he knows he will not be able to complete Shemoneh Esrei before the chazan reaches any of these devarim shebekedusha, he may not begin Shemoneh Esrei until he responds to the chazan. At Shacharis, he should pause at Shira Chadosha so that there will not be a delay between the completion of Goal Yisroel and Shemoneh Esrei. If one has already responded to (or anticipates that he will respond to) Kedusha or Borchu that day, he does not need to wait. If one has already responded to Kaddish, the poskim disagree about whether he must wait for the chazan. One may not begin Shemoneh Esrei if he will not be done by the time the chazan reaches Modim. Otherwise, he may find himself in the middle of a different brocha and will be unable to bow when the tzibur is bowing. According to the Rema, a person may only start if he is certain that he will not still be in the middle of Shemoneh Esrei when the chazan reaches the end of the brochos of Hakel Hakodosh and Shomeya Tefilla.   



סי' ק"ט ס"א ס"ק א'-ה'

Does a person who davens a lengthy Shemoneh Esrei have to wait to begin until her hears Kedusha?

According to some Achronim, the above halachos only apply if a person begins after the tzibur. If one begins with the tzibur, even if he knows that his davening is lengthy and he will miss responding to Kedusha, Modim or Kaddish, he does not have to wait for the chazan. If a person estimates that by replacing the brochah of Sim Sholom with the text of Sholom Rov he will finish  davening in time for Kedusha, the poskim disagree about whether replacing the text is permitted. During Aseres Yemei Teshuvah, one should not omit B’sefer Chaim just so that he can complete Shemoneh Esrei in time for Kedusha.

ביה"ל ד"ה הנכנס ביאורים ומוספים דרשו 11

Is it necessary to travel to respond to devarim shebekedusha?

Among the various devarim shebekedusha, some have priority over others. If one is only able to listen to one of them, or if he hears two of them simultaneously from two separate minyanim, he should respond to the more important one. The following is the list in order of priority: Amen Y’hei Shmei Rabba, Kedusha, Modim, Borchu, and answering Amen to the brochos of Hakel Hakodosh and Shema Koleinu. It should be noted that all these devarim shebekedusha supersede tefilla b’tzibur but do not have priority over connecting geulah to tefilla. Therefore, one should not answer to any devarim shebekedusha after he completes Goal Yisroel. Although there is a halacha that one must travel a certain distance for tefilla b’tzibur, there does not seem to be any such obligation for responding to devarim shebekedusha.

ביה"ל ד"ה לקדושה ביאורים ומוספים דרשו 14

• A person who did not daven Ma’ariv on Motzei Shabbos must daven two tefillos on Sunday morning. If he already said Havdalah, he does not say Atah Chonantonu during either Shemoneh Esrei.

• If one forgot Ya’aleh V’yavo on Hoshanah Rabba at Mincha, he will not be able to daven two tefillos during Ma’ariv, since that tefilla will only be mentioning Shemini Atzeres and not Sukkos. Also, nedavos are not accepted on Yom Tov.

• In the opinion of many Achronim, making an inappropriate addition to Shemoneh Esrei is similar to talking and necessitates returning to the beginning of the brocha. B’dieved, though, if the brocha was completed and one continued further in Shemoneh Esrei, he does not have to go back. 

• Is it ever permissible to say Kedusha in the middle of Shemoneh Esrei?

• Is davening along with the chazan considered tefilla b’tzibur?

• Is a person who is davening along with the chazan obligated to adopt his nusach?