The HSN (Harmonized System of Nomenclature) code for gumboots, which is a type of waterproof footwear generally made of rubber or plastic, falls under heading 6401. This heading covers waterproof footwear having outer soles and uppers of rubber or plastic.
Here is a description:
64: Footwear, gaiters and other similar articles; Parts of such goods
01: Waterproof footwear having outer soles and uppers of rubber or plastic, the upper of which is neither joined nor attached to the sole by stitching, riveting, nailing, screwing, plugging or similar processes
Specifically, gumboots classified under:
6401.10: Footwear with protective metal toe-caps
6401.92: Other, covering the ankle but not covering the knee
6401.99: Other
For GST purposes in India, the GST rate for goods classified under HSN code 6401 is generally 18%.