Answered by Ustadha Iman Badawi
May One Delay Taslim With the Imam to Recite the Salawat ?
In the Name of Allah, Most Merciful and Compassionate
Assalamu ‘Alaykum Dear Brother in Faith,
If the Imam has completed the prayer and the follower has yet to complete the tashahhud, they must complete it first and then end the prayer. This is because the recitation of the tashahhud is a mandatory (wajib) element of the prayer.
If, however, all that remains is to recite the salawat and supplications before the taslim, one should end the prayer with the Imam without delay. This is because the recitation of salawat and supplications is a sunna act.
[Shurunbulali, Maraqi al-Falah 2:204-5]
Allah, Most High, knows best.
Checked and Approved by Shaykh Faraz Rabbani