Equitable bar against retrospective recovery of statutory levies in execution proceedings

prohibits a principal employer from unilaterally adjusting unlevied statutory cess against an arbitral decree when such claim was never raised during the substantive dispute resolution. Principles of natural justice and finality of dispute resolution prevent an employer from remaining silent about cess deductions during primary arbitral hearings and subsequent challenge proceedings under Sections 34 and 37, only to orchestrate unilateral deductions during execution. Attempting to withhold awarded sums in execution on the strength of subsequent, retroactive government circulars issued years after contract termination represents an impermissible afterthought. An executing court cannot go behind a conclusive arbitral award to entertain fresh set-offs or impose retroactive tax liabilities on a terminated contractor who was never assessed during the currency of the project. (Prakash Atlanta (JV) Vs National Highways Authority of India | 2026 INSC 76).