Late Tachanun

If a person davens mincha and his shemoneh esrei is longer than the tzibbur’s and when he finishes the tzibbur is up to aleinu, should the individual say aleinu with the tzibbur and then say tachanun, or say tachanun and not say aleinu with the tzibbur?
Thank You

Answer:

Under such circumstances, it is correct to say the first paragraph of Tachanun straight after the shemoneh esrei. After the first paragraph of tachanun is complete, one should say aleinu with the tzibbur (whatever one can), and following this, one should make up the rest of tachanun.

The reason for this is that although aleinu should be said with the tzibbur, the proper place for tachanun is immediately after davening, and davening with tachanun is termed tefillah arichta (a long prayer, an idea mentioned by the Beis Yosef and other poskim).

A similar ruling is given by Shut Kenei Bosem and by Shut Mishnas Yosef.