Hey Carlos, according to the spec, verifyingContract isn’t strictly required. Only “one or more” domain separator field is needed.

However, the reason that you might want to include it is that the on-chain contract (which receives the signature and data) can use thethis keyword, which refers to the contract’s own address, when it verifies the signature.

https://github.com/ethereum/EIPs/blob/master/EIPS/eip-712.md#definition-of-domainseparator