The Timing of the Prostration of Forgetfulness Relative to Salām
Is the prostration of forgetfulness performed before or after Salām?
Hanafi
The prostration of forgetfulness is performed entirely after Salām, whether for addition or omission.
Reference: Al-Hidāyah — Radd al-Muḥtār — Badāʾiʿ al-Ṣanāʾiʿ
Maliki
Sujūd al-Sahw is before Salām for omissions, after for additions, and before if combined.
Reference: Al-Sharḥ al-Kabīr — Al-Kharashī ʿalā Khalīl — Ḥāshiyat al-Dasūqī
Shāfiʿī
The prostration of forgetfulness is always performed immediately before the Salām in all cases.
Reference: Rawḍat al-Ṭālibīn — Al-Majmūʿ — Tuḥfat al-Muḥtāj
Hanbali
The prostration of forgetfulness is recommended before the salām, except when one gives the salām having omitted a rakʿah or more, in which case he prostrates after it; some add the case of the imam building on his predominant assumption, for those who hold that view.
Reference: Kashshāf al-Qināʿ — Sharḥ Muntahā al-Irādāt — Zād al-Mustaqniʿ