Service of the intimation under Section 143(1) is mandatory...

Service of the intimation under Section 143(1) is mandatory before a tax demand can be enforced, and a refund cannot be adjusted against a demand that is not shown to exist and have been served. The department produced only portal screenshots and no copy of the intimation or proof of service, so the alleged demand was treated as unenforceable. On that basis, the High Court quashed the impugned demand and the consequential interest, and held that adjustment of the later-year refund against that demand was impermissible.