CN code 5503 90 covers other staple fibres of synthetic materials, not carded, combed, or processed for spinning, not falling within other subheadings of heading 5503. This is a residual category covering staple fibres from synthetic polymers not specified in subheadings 5503 11 to 5503 40, such as polyolefins, elastanes, speciality polyamides, and other synthetic textile fibres. Classification requires the fibres to be synthetic, staple, and not processed for spinning. Importers should hold a technical specification covering polymer type, cut length, fineness, and physical properties.

Importing synthetic fibres under CN code 5503 90 into the EU is subject to the Union Customs Code. Synthetic fibres are subject to REACH — importers should verify that production substances do not contain SVHC. The Textile Regulation requires correct fibre composition labelling. Import documentation includes an invoice, technical specification, SDS, and certificate of origin.

Synthetic staple fibres under CN code 5503 90 are a diverse category covering speciality synthetic fibres. Major exporters include China, Japan, Korea, and the USA. Correct classification requires polymer identification and distinction from polyester (5503 20), polyamide (5503 11/19), acrylic (5503 30), and polypropylene (5503 40) fibres.

CN code 5503 90 covers other synthetic staple fibres not listed in other subheadings. These may include polypropylene, polyamide or other synthetic polymer fibres. They are used as raw materials in the textile industry, nonwoven production and geotextiles. For customs classification, the exact polymer type must be identified, as some fibres have their own codes in subheadings 5503 11–5503 40.