Estonian negated indicative clauses show no agreement, whereas Estonian negated imperative clauses show agreement twice: once on the main verb and once on the negation word ära. This contrasts with affirmative clauses, where agreement appears only once. I propose a unified syntax for agreement across these clausal types, arguing that the there is one head which bears a φ-feature probe in all Estonian sentences. There is no agreement in negated indicatives because this head has only one suitable vocabulary item in this context: ei. Doubled agreement arises due to a rule of post- syntactic Feature Copying in imperative contexts. I argue that this analysis is superior to an analysis making use of multiple φ-feature probes in the syntax, as such analyses struggle to account for the optionality of doubling in first-person plural contexts. The proposed analysis makes predictions about the kinds of marking possible in negated imperatives, which appear to be borne out in related Uralic languages. This investigation supports a view of the morphosyntax of agreement whereby the syntax and morphology of agreement overlap but do not coincide.