Joint and several liability of partners continues after firm dissolution, preserving tax assessment and penalty obligations. Section 189 requires assessing the firm's total income post-dissolution or discontinuance as if no change occurred, with all Income-tax Act provisions, including penalties, applying. Partners at the time of dissolution and legal representatives of deceased partners are jointly and severally liable for tax, penalty and other sums for all assessment years since formation. Ongoing assessment proceedings may continue against those persons from their current stage, and authorities may impose penalties under Chapter XXI if specified misconduct is established.