Tier 1/beyond Tier 1 is unknown
Statement claims that practices such as human trafficking, forced labour, physical abuse, restricting freedom of movement, confiscation of passports and other documentation, unsafe work environments, failure to pay adequate wages, excessive or forced overtime, illegal child labour, and many other aspects of worker welfare are "addressed" by the Code.
No specifics further than this
The company report code is applicable to suppliers and sub-suppliers.
pg. 1-2
"Costco's Supplier's Code of Conduct"