Tax demand payment defaults trigger interest, instalment relief, appeal protection, and limited waiver powers under recovery provisions. Tax demanded under a notice of demand must be paid within thirty days, or within a shorter approved period, failing which simple interest at 1% per month or part month applies unless excluded by law. The Assessing Officer may extend time or allow instalments, and higher authorities may reduce or waive interest on hardship, control, and cooperation grounds. Non-payment within time results in the assessee being deemed in default, subject to discretion during appeal and special protection for income outside India where remittance is restricted.