On the ECAA1 application, it has sections for filling out dependant (partner) information, but the application itself makes no mention of supporting documents for dependants. I know some people have filled it out, provided the relevant dependant visa and passport with no other documentation and the partner has been granted a dependant visa.
But looking at the family members information page on https://www.gov.uk/turkish-worker/family-members it lists documents to provide, including:
- for your partner, a marriage certificate or proof you’ve lived together for at least 2 years if you’re not married
proof your partner or child are living permanently with you, eg utility bills, bank statements, other official documents (such as NHS letters) with your address on them