Deemed credit for inputs in apparel manufacture allowed for offset against excise duty on final products upon clearance. Declares specified fabrics and other raw materials as declared inputs and articles of apparel and clothing accessories not knitted or crocheted as final products. The duty (excise or additional duty under section 3 of the Customs Tariff Act) on declared inputs shall be deemed to have been paid and the deemed credit is fixed at an amount equivalent to 20 per cent. of the duty leviable on the declared final products; such credit is allowed to the manufacturer at the time of clearance of the final products without production of documents evidencing payment on the inputs.