סימן כא סעיף א

כְּבָר נִתְבָּאַר בְּסִימָן י"ח שֶׁאִם עָבַר זְמַן תְּפִלָּה בְּמֵזִיד, אֵין לוֹ תַּשְׁלוּמִין אֲבָל אִם מֵחֲמַת שְׁגָגָה אוֹ אֹנֶס לֹא הִתְפַּלֵּל, אוֹ שֶׁטָּעָה בִּתְפִלָּתוֹ בְּדָבָר שֶׁצָּרִיךְ לַחְזֹר וּלְהִתְפַּלֵּל יָכוֹל לְהַשְׁלִימָהּ לְאַחַר תְּפִלָּה הַסְּמוּכָה לָהּ, וְצָרִיךְ שֶׁיִּתְפַּלֵּל דַּוְקָא תְּפִלָּה שֶׁהִיא זְמַנָּהּ, וְאַחַר כָּךְ תְּפִלַּת הַתַּשְׁלוּמִין, דְּהַיְנוּ אִם לֹא הִתְפַּלֵּל שַׁחֲרִית, אֲזַי כְּשֶׁיַּגִּיעַ זְמַן תְּפִלַּת מִנְחָה, יִתְפַּלֵּל מִתְּחִלָּה, תְּפִלָּה לְשֵׁם מִנְחָה וְאוֹמֵר תַּחֲנוּן, וְאַחַר כָּךְ מִיָּד אוֹמֵר אַשְׁרֵי, וּמִתְפַּלֵּל עוֹד שְׁמֹנֶה עֶשְׂרֵה בִּשְׁבִיל שַׁחֲרִית. וְאִם לֹא הִתְפַּלֵּל מִנְחָה, אֲזַי יִתְפַּלֵּל תְּחִלָּה עַרְבִית, וְיִשְׁהֶה רַק כְּדֵי הִלּוּךְ דּ' אַמּוֹת וְאֵינוֹ אוֹמֵר אַשְׁרֵי אֶלָּא מִיָּד יִתְפַּלֵּל תְּפִלַּת שְׁמֹנֶה עֶשְׂרֵה בִּשְׁבִיל מִנְחָה, וְאִם לֹא הִתְפַּלֵּל עַרְבִית, אֲזַי לְאַחַר תְּפִלַּת שַׁחֲרִית, יֹאמַר תַּחֲנוּן וְאַשְׁרֵי, וְיִתְפַּלֵּל תְּפִלַּת שְׁמֹנֶה עֶשְׂרֵה לְשֵׁם עַרְבִית וְאַחַר כָּךְ יֹאמַר לַמְנַצֵּחַ וּבָא לְצִיּוֹן וְכוּ', וְאָסוּר לוֹ לֶאֱכֹל עַד שֶׁיִּתְפַּלֵּל גַּם תְּפִלָּה זוֹ, שֶׁהִיא לְשֵׁם עַרְבִית.

Preface:
The general rule is that omitting one of the prayers requires a make-up-prayer. This will compensate for having omitted a tefillah, but only where the omission occurred unwillingly (אוֹנֵס) or unintentionally (שׁוֹגֵג). But if one willfully and deliberately omitted a tefillah, there is no way to compensate. An important fact to keep in mind while studying this chapter: The compensation tefillah is performed by repeating the particular tefillah that is due at that time. For example, if at Maariv one compensates for an omitted Mincha, he does this by praying two Maariv Shemoneh Esrei's. Due to this, a number of unique situations arise: e. g. Omitting Mincha on Friday afternoon requires two Maariv Shemoneh Esreis on Friday night, both, being the Shabbos eve Shemoneh Esreis.This chapter discusses the form this compensation takes as well as what is considered deliberate and what is considered unintentional and unwilling.
It has already been explained (in Chapter Eighteen) that if [you allowed] the time of tefillah to pass intentionally, there is no compensation. But if [it was] unintentional, or due to something beyond your control, that you did not pray, or [if you did pray, but] erred in your tefillah in a way that requires that you repeat the tefillah,¹And you first became aware of your error after the time for this teflllah had passed. [then] you may compensate for it following the next tefillah.²E.g. if you missed Shacharis or erred at Shacharis then you must compensate at Minchah; if you missed Minchah then you compensate at Maariv etc. You must first pray the tefillah that is due at that time and [only] afterwards the make-up tefillah, for example: if you did not pray the Shacharis tefillah, then when the time for Minchah arrives, you first pray a tefillah for Minchah, followed by the Tachanun prayer, and immediately afterwards you should say Ashrei, and then pray another Shemoneh Esrei for the sake of [the omitted] Shacharis. [Similarly] if you omitted Minchah, then you should first say the Maariv prayer, and then pause only for the time it takes to walk four amos, do not say Ashrei, but, immediately, pray the Shemoneh Esrei prayer for the sake of [the omitted] Minchah. [Similarly] if you omitted Maariv, then after the Shacharis prayer you should say Tachanun and Ashrei, and [then] pray the Shemoneh Esrei prayer for the sake of Maariv. After that you should say Lamenatzeiach and Uva letzion, etc. You may not eat until you also complete the make-up tefillah, which is for the sake of Maariv.

תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)