Notice of demand: payment required under Income-tax Act; interest, recovery measures and specified appeal routes apply. Notice under section 156 demands payment of a determined sum within the prescribed period to the authorised bank, with an enclosed challan; shortened periods require prior approval. Non-payment attracts interest on arrears under section 220(2), possible penalty proceedings under section 221, and recovery under the Act's recovery provisions. The notice sets out appeal routes under Chapter XX (Forms No. 35 and 36) and procedural instructions for cheque payment, and applications for extension or instalments before the payment deadline.