Tahanun is not said on Erev Shabbat and Erev Yom Tov. It is also not said on the following days: Rosh Hodesh, Hanukka, Tu BiShvat, the 14th and 15th of Adar I, Purim and Shushan Purim, Yom HaAtzma'ut, Lag BaOmer, Yom Yerushalayim, Tisha B'Av, Tu B'Av, and the preceding afternoons, the month of Nisan, the 14th of Iyar (Pesah Sheni), from Rosh Hodesh Sivan through the day after Shavuot (in Israel through 12th of Sivan), and from Erev Yom Kippur through the day after Simhat Torah (in Israel through Rosh Hodesh Marheshvan). Tahanun is also not said: on the occasion of a Brit Mila, either where the brit will take place or where the father, Sandak or Mohel are present; if a groom is present (and some say, a bride) on the day of his wedding or during the week of Sheva Berakhot; in a house of mourning.
Hebrew
אֱלֹהֵינוּ וֵאלֹהֵי אֲבוֹתֵינוּ
תָּבוֹא לְפָנֶיךָ תְּפִלָּתֵנוּ, וְאַל תִּתְעַלַּם מִתְּחִנָּתֵנוּ
שֶׁאֵין אָנוּ עַזֵּי פָנִים וּקְשֵׁי עֹרֶף לוֹמַר לְפָנֶיךָ
יהוה אֱלֹהֵינוּ וֵאלֹהֵי אֲבוֹתֵינוּ
צַדִּיקִים אֲנַחְנוּ וְלֹא חָטָאנוּ
אֲבָל אֲנַחְנוּ וַאֲבוֹתֵינוּ חָטָאנוּ
Israeli
Eloheinu veilohei avoteinu
tavo lefanecha t'filatenu, ve-al titalam mitechinatenu
she-ein anu azei fanim ukshei oref lomar lefanecha
Adonai Eloheinu veilohei avoteinu
tzadikim anachnu velo chatanu
aval anachnu va-avoteinu chatanu
Strike the left side of the chest with the right fist while saying each of the sins:
Hebrew
אָשַׁמְנוּ, בָּגַדְנוּ, גָּזַלְנוּ, דִּבַּרְנוּ דֹּפִי
הֶעֱוִינוּ, וְהִרְשַׁעְנוּ, זַדְנוּ, חָמַסְנוּ, טָפַלְנוּ שֶׁקֶר
יָעַצְנוּ רָע, כִּזַּבְנוּ, לַצְנוּ, מָרַדְנוּ, נִאַצְנוּ
סָרַרְנוּ, עָוִינוּ, פָּשַׁעְנוּ, צָרַרְנוּ, קִשִּׁינוּ עֹרֶף
רָשַׁעְנוּ, שִׁחַתְנוּ, תִּעַבְנוּ, תָּעִינוּ, תִּעְתָּעְנוּ.
Israeli
ashamnu, bagadnu, gazalnu, dibarnu dofi
he-evinu, vehirshanu, zadnu, chamasnu, tafalnu sheker
ya-atznu ra, kizavnu, latznu, maradnu, ni-atznu
sararnu, avinu, pashanu, tzararnu, kishinu oref
rashanu, shichatnu, ti-avnu, ta-inu, titanu.
Neh. 9
Hebrew
סַרְנוּ מִמִּצְוֹתֶיךָ וּמִמִּשְׁפָּטֶיךָ הַטּוֹבִים, וְלֹא שָׁוָה לָנוּ.
וְאַתָּה צַדִּיק עַל כָּל־הַבָּא עָלֵינוּ, כִּי־אֱמֶת עָשִׂיתָ
וַאֲנַחְנוּ הִרְשָׁעְנוּ:
Israeli
sarnu mimitzvotecha umimishpatecha hatovim, velo shavah lanu.
ve-atah tzadik al kol-haba aleinu, ki-emet asita
va-anachnu hirshanu: