Answered by Shaykh Sohail Hanif, SunniPath Academy Teacher
Is it permissible to join the jammat when the Imam is in tashahudd of the last rakat of the jumma prayer? i.e. would one’s jumma namaz be fulfilled if he read takbir and joined jammat before the imam has read the salaam?
Imam al-Tumurtashi mentions in his very central matn (primer) in Hanafi fiqh, Tanwir al-Absar,
Whoever joins it [the Friday prayer] in the final sitting [tashahhud] or the forgetfulness prostration, completes the prayer as a Friday prayer. (Tanwir al-Absar, published with Radd al-Muhtar 1:550, Bulaq)
This means that if one joined at the end of the Friday prayer one gets up and makes up two rakats and that the prayer counts as a Friday prayer.