During Baruch She’Amar
22. The bracha of Baruch She’Amar is divided into three parts with respect to answering Amen during the bracha.
23. Until ברוך אתה ה'. One may answer Amen to any bracha, even someone else’s Baruch She’Amar, between the beginning of the bracha and the first “ברוך אתה ה'.” One may likewise say Modim d’Rabanan with the tzibbur and then go back to the beginning of the bracha (הגר''ח קנייבסקי, אשי ישראל סוף הספר תשו' רט''ו ).
24. From the first ברוך אתה ה' until the second one. Even after one begins the first “ברוך אתה ה',” he may answer Amen to any bracha other than another person’s Baruch She’Amar (מ''ב סי' נ''א סק''ב ).
25. Second ברוך אתה ה'. During the closing of the bracha, i.e., after beginning to say the second "ברוך אתה ה'," one may not answer Amen to any bracha (חיי אדם, מ''ב שם ). One may similarly not answer “Amen yehei shmei raba...” (חיי אדם כלל ה').
During Yishtabach
26. Until ברוך אתה ה'. From the beginning of the bracha until “ברוך אתה ה',” one may answer Amen to any bracha other than to someone else finishing Yishtabach.
27. From ברוך אתה ה'. After one begins “ברוך אתה ה',” he may not answer Amen to any bracha (מ''ב שם ).
During Pesukei d’Zimra
28. One must be careful to avoid speaking from the time he starts Baruch She’Amar until the end of Shemoneh Esrei (שו''ע סי' נ''א ס''ד). Since Baruch She’Amar is the bracha before Pesukei d’Zimra and Yishtabach is the bracha at the end of Pesukei d’Zimra, one may not interrupt between them for a non-mitzva purpose (מ''ב סק''ו). However, there are certain words of kedusha one may say in the middle, as will be explained.
29. אמן . One may say Amen to any bracha he hears. This is true even in the middle of a pasuk, as long as it is the end of a clause (מ''ב סק''ח ).
30. ברוך הוא וברוך שמו . One may not say ברוך הוא וברוך שמו when someone else says Hashem’s name in a bracha. Since it is just a minhag, not a chiyuv, we do not interrupt Pesukei d’Zimra for it (מ''ב שם, שו''ת אג''מ או''ח ח''ב סוף סי' ט''ז ). Similarly, one may not say בריך הוא in Kaddish.
31. אשר יצר . One may say Asher Yatzar after relieving himself mid-Pesukei d’Zimra (מ''ב שם ), but it should be said between kapitlach [בין הפרקים ]. If one suddenly left before Yishtabach, it is best to say some pesukim, e.g., Ashrei, before saying Yishtabach so that the bracha of Yishtabach can take effect on the pesukim of praise (ביאה''ל סי' נ''ג ס''ב ד''ה וקצת ).
32. מודים דרבנן . One may interrupt for Modim d’Rabanan (מ''ב שם ). He should say the entire paragraph (שו''ת מנחת יצחק ח''ט סי' ח'), not just the first three words, as we do during Birchos Kriyas Shema (מ''ב סי' ס''ו סק''כ ).
33. Words of kedusha. One may interrupt to say words of kedusha with the tzibbur, e.g., Kaddish, Kedusha, and Barchu (מ''ב סק''ח ). When interrupting for Kedusha, it is best to be quiet for the entire duration of Kedusha, not just during the responses (חיי אדם כלל ע' אות ד').
34. Bracha on thunder, lightning. If one hears thunder or sees lightning, he may say the appropriate bracha during Pesukei d’Zimra, as the opportunity for the bracha will pass (ח "א כלל כ אות ג ).
35. Eating, drinking. One may not eat or drink during Pesukei d’Zimra, as the act of eating or drinking itself is an interruption, unless there is a great necessity due to weakness, health, or the like. If there is a need to eat or drink, it is best to say a bracha before Baruch She’Amar and eat or drink a bit so that there will be no need to interrupt Pesukei d’Zimra for the bracha too. However, if one did not say a bracha beforehand, he can say it during Pesukei d’Zimra (פסקי תשובות סי' נ''א אות ט').
36. Borei Nefashos. Similarly, if one ate or drank before Baruch She’Amar and forgot to say Borei Nefashos, and he is worried the time to say the bracha will run out, he may say Borei Nefashos during Pesukei d’Zimra, as it is a bracha with a limited timeframe.
37. Kriyas Shema. If one is mid-Pesukei d’Zimra and sees that sof zman Kriyas Shema is coming, he may interrupt to say Kriyas Shema, as that is an interruption for a mitzva purpose (מ''ב שם סק''י ).
38. Birchos HaTorah. Similarly, if one forgot to say Birchos HaTorah before davening and remembers in the middle of Pesukei d’Zimra, he may interrupt to say Birchos HaTorah and the pesukim said afterward (מ''ב שם ).
39. Bracha on tallis, tefillin. Some say that if one only got a tallis or tefillin in the middle of Pesukei d’Zimra, or he was not able to put them on earlier due to various circumstances, he may put them on right away with the regular brachos. He should try to put them on between kapitlach (מ''ב סי' נ''ג סק''ה ). Obviously he should not say Barchi Nafshi before putting on the tallis or L’sheim Yichud before the tefillin (ברכת הבית שער ל''ט סקי''ד ).
40. Others argue. They hold he should wait until after Yishtabach, before Kaddish, to put them on, since there is no need to make a bracha on them specifically during Pesukei d’Zimra (שו''ע הרב ס''ג, חיי אדם כלל כ' ס''ג, שו''ת וישב משה ח''א סי' צ'). He should not put them on between the end of Pesukei d’Zimra and Yishtabach, as that would be an interruption before the bracha (שו''ע סי' נ''ג ס''ג ).
