Siman 181
Presented here for study, not as a practical ruling. The Shulchan Aruch rules by Sephardi custom, the Rema's glosses by Ashkenazi custom, and the Kitzur follows Ashkenazi custom. For a practical question, ask your rabbi.
א פְּאוֹת הָרֹאשׁ הֵם שְׁתַּיִם. סוֹף הָרֹאשׁ הוּא מְקוֹם חִבּוּרוֹ לַלֶּחִי מִיָּמִין וּמִשְּׂמֹאל.
1 The Issur of Shaving the Pe'ot, 12 Seifim: There are two pe'ot/corners of the head. [Where the] head ends is where it joins with the jaw, on the right and on the left.
ב בֵּין שֶׁגִּלַּח הַפֵּאוֹת בִּלְבַד, בֵּין שֶׁגִּלַּח כָּל הָרֹאשׁ עִם הַפֵּאוֹת, חַיָּב.
2 Whether one shaves the pe'ot only, or whether he shaves the whole head with the pe'ot, he is liable.
ג אֵינוֹ חַיָּב אֶלָּא בְּתַעַר. וְיֵשׁ אוֹסְרִים בְּמִסְפָּרַיִם כְּעֵין תַּעַר, וְיֵשׁ לָחוּשׁ לְדִבְרֵיהֶם.
3 He is not liable unless he uses a razor. And there are those who forbid scissors that shave like a razor; and their words should be regarded.
ד גַּם הַנִּקָּף חַיָּב אִם סִיַּע בַּדָּבָר שֶׁמַּטֶּה עַצְמוֹ אֵלָיו לְהַקִּיפוֹ, אֲבָל אִסוּרָא אִכָּא אַף עַל פִּי שֶׁלֹּא סִיַּע, לְפִיכָךְ אָסוּר לִהְיוֹת נִקָּף אֲפִלּוּ עַל יְדֵי עוֹבֵד כּוֹכָבִים
4 The person whose pe'ot are shaved off is also liable if he assists in shaving, leaning his head to him so that he shaves his pe'ah, but there is prohibition even if he does not help, therefore it is forbidden to have one's pe'ot shaved off even by means of an idolater.
ה הַמַּקִּיף אֶת הַקָּטָן, חַיָּב. אֲבָל מֻתָּר לְהַקִּיף אֶת הָעוֹבֵד כּוֹכָבִים אוֹ אֶת הָאִשָּׁה. (בֵּית יוֹסֵף בְּשֵׁם הָרֹא"שׁ). וְיֵשׁ מִסְתַּפְּקִים בַּדָּבָר (בֵּית יוֹסֵף בְּשֵׁם י"א). וְקָטָן, מֻתָּר לִהְיוֹת נִקָּף מִן הָעוֹבֵד כּוֹכָבִים (ר"ן פֶּרֶק אֵלּוּ הֵן הַגּוֹלִין).
5 One who rounds [the head of] a minor male is liable. (But it is permitted to round [the head of] an idolater or a woman -- Beit Yosef, in the name of the RoSh). But there are those who have doubt regarding this (Beit Yosef in the name of י"א). A minor is permitted to be rounded by an idolater (Ran, in the perek Eilu Hen Hagolin).
ו אִשָּׁה אֵינָהּ בְּמִצְוַת הַקָּפָה, וְיֵשׁ אוֹמְרִים שֶׁאַף עַל פִּי שֶׁמֻּתֶּרֶת לְהַקִּיף פְּאַת רֹאשָׁהּ, אֲסוּרָה לְהַקִּיף פְּאַת רֹאשׁ הָאִישׁ וַאֲפִלּוּ הוּא קָטָן.
6 A woman is not included in the mitzvah of rounding, but there are those who say that although she is permitted to round the corner of her head, she is forbidden to round the corner of the head of a man, even if he is a minor.
ז עֲבָדִים חַיָּבִים בְּהַקָּפַת הָרֹאשׁ כַּאֲנָשִׁים.
7 Slaves are obligated regarding rounding the head, just as [free] men.
ח טֻמְטוּם וְאַנְדְּרוֹגִינוֹס אֲסוּרִין בְּהַקָּפַת הָרֹאשׁ.
8 A tumtum or androgynos is forbidden to round the head.
ט שִׁעוּר הַפֵּאָה מִכְּנֶגֶד שֵׂעָר שֶׁעַל פַּדַחְתּוֹ וְעַד לְמַטָּה מִן הָאֹזֶן, מָקוֹם שֶׁהַלֶּחִי הַתַּחְתּוֹן יוֹצֵא וּמִתְפָּרֵד שָׁם, וְכָל רֹחַב מָקוֹם זֶה לֹא תִּגַּע בּוֹ יָד.
9 The extent of the pe'ah [of the head] is from the hair on [i.e. by] his forehead including up to below the ear, where the lower jaw emerges and separates [from the head] there, and no hand should touch the entire width of this place.
י אֵינוֹ חַיָּב עַל הַשְׁחָתַת פְּאַת הַזָּקָן אֶלָּא בְּתַעַר, אֲבָל בְּמִסְפָּרַיִם מֻתָּר, אֲפִלּוּ כְּעֵין תַּעַר. הַגָּה: וּמִכָּל מָקוֹם נִזְהָרִים כְּשֶׁמִּסְתַפְּרִין בְּמִסְפָּרַיִם שֶׁיַּעֲשֶׂה הֶקֵּף הַגִּלּוּחַ בַּחֵלֶק הָעֶלְיוֹן מִן הַמְסַפְּרוֹת וְלֹא בַּתַּחְתּוֹן, פֶּן יַעֲשֶׂה הַכֹּל עִם חֵלֶק הַתַּחְתּוֹן וְהָוֵי כְּתַעַר (ת"ה סִימָן רצ"ה). מִיהוּ נִרְאֶה דְּתַחַת הַגָּרוֹן אֵין לָחוּשׁ בָּזֶה, הוֹאִיל וְאֵינוֹ עִקַּר מְקוֹם הַפֵּאוֹת (ד"ע).
10 One is not liable in destroying the corner of the beard except by means of a razor, however by scissors it is permitted, even cutting so close as a razor. Rema: But in any case we are cautious when trimming with scissors to do the shaving motion with the upper piece of the scissors and not with the bottom piece, lest one does it all with the bottom piece and it be as a razor (See Siman 395). Anyhow, it seems that under the throat there is no concern about this, since it is not the main location of the pe'ot.
יא פְּאוֹת הַזָּקָן הֵם ה', וְרַבּוּ בָּהֶם הַדֵּעוֹת, לְפִיכָךְ יְרֵא שָׁמַיִם יֵצֵא אֶת כֻּלָּם וְלֹא יַעֲבִיר תַּעַר עַל כָּל זְקָנוֹ כְּלָל. וַאֲפִלּוּ תַּחַת הַגָּרוֹן (בֵּית יוֹסֵף בְּשֵׁם אִגֶּרֶת ר"י וּסְמַ"ג).
11 There are five corners of the beard, and there are many opinions on them, therefore a God-fearing man should fulfill all of them and not pass a razor over any of his beard at all. (And even under the throat) (Beit Yosef in the name of the Iggeret R"Y and the Smag)
יב אִשָּׁה שֶׁיֵּשׁ לָהּ זָקָן, מֻתֶּרֶת לְהַשְׁחִיתוֹ; וְדִינָהּ בְּהַשְׁחָתַת זְקַן הָאִישׁ, כְּדִינָהּ בְּהַקָּפַת רֹאשׁ הָאִישׁ.
12 A woman who has a beard is permitted to destroy it; and the law for her in destroying the beard of a man is the same as in rounding the head of a man.