What is the tolerance threshold under the EU-Mexico?

The general tolerance is 10% of the ex-works value of the finished product.

EU-Mexico - HS 42

EU-Mexico Global Agreement (FTA part)

1 RegelnToleranz: 10%2000

4200-4299Articles of leather; saddlery and harness; travel goods, handbags and similar containers; articles of animal gut (other than silk worm gut)

Manufacture in which all the materials used are classified within a heading other than that of the product.