diff --git a/src/email-subscribers/metadata.ts b/src/email-subscribers/metadata.ts
new file mode 100644
index 00000000..e1a75a37
--- /dev/null
+++ b/src/email-subscribers/metadata.ts
@@ -0,0 +1,23 @@
+// Schema for the `metadata` jsonb column on `publication_email_subscribers`.
+//
+// The column is nullable — most rows have no metadata at all (organic
+// signups). Within each variant, only the `source` discriminator is
+// required; every other field is optional because different writers
+// populate different subsets.
+
+export type CsvImportProvenance = {
+  source: "csv_import";
+  imported_at?: string;
+  // Other CSV columns that the import script didn't consume directly
+  // (e.g. ip_address, signup_source) — kept verbatim so we don't lose
+  // information from the source list. The subscription date is not
+  // stored here; it lives on `created_at`/`confirmed_at`.
+  csv_columns?: Record<string, string>;
+};
+
+// Discriminated union of known subscriber-row metadata shapes. Extend as
+// new sources start writing the column.
+export type SubscriberMetadata = CsvImportProvenance;
+
+// Column-level type — most rows are null.
+export type SubscriberMetadataColumn = SubscriberMetadata | null;
diff --git a/supabase/migrations/20260507205333_add_subscriber_metadata.sql b/supabase/migrations/20260507205333_add_subscriber_metadata.sql
new file mode 100644
index 00000000..c5deba00
--- /dev/null
+++ b/supabase/migrations/20260507205333_add_subscriber_metadata.sql
@@ -0,0 +1,7 @@
+-- Provenance metadata on email subscribers (e.g. csv_import, imported_at,
+-- original_subscription_date). The events table already has its own
+-- per-event metadata column; this one tags the subscriber row itself so
+-- "where did these subscribers come from" is a one-table query.
+
+alter table "public"."publication_email_subscribers"
+  add column "metadata" jsonb;