diff --git a/backend/src/main/resources/db/migration/V18__add_transcription_blocks.sql b/backend/src/main/resources/db/migration/V18__add_transcription_blocks.sql
new file mode 100644
index 00000000..03e5aaf8
--- /dev/null
+++ b/backend/src/main/resources/db/migration/V18__add_transcription_blocks.sql
@@ -0,0 +1,16 @@
+CREATE TABLE transcription_blocks (
+    id            UUID             PRIMARY KEY DEFAULT gen_random_uuid(),
+    annotation_id UUID             NOT NULL REFERENCES document_annotations(id) ON DELETE CASCADE,
+    document_id   UUID             NOT NULL REFERENCES documents(id) ON DELETE CASCADE,
+    text          TEXT             NOT NULL DEFAULT '',
+    label         VARCHAR(200),
+    sort_order    INTEGER          NOT NULL DEFAULT 0,
+    version       INTEGER          NOT NULL DEFAULT 0,
+    created_by    UUID             REFERENCES app_users(id) ON DELETE SET NULL,
+    updated_by    UUID             REFERENCES app_users(id) ON DELETE SET NULL,
+    created_at    TIMESTAMP        NOT NULL DEFAULT now(),
+    updated_at    TIMESTAMP        NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_tb_document_sort ON transcription_blocks(document_id, sort_order);
+CREATE INDEX idx_tb_annotation    ON transcription_blocks(annotation_id);
diff --git a/backend/src/main/resources/db/migration/V19__add_transcription_block_versions.sql b/backend/src/main/resources/db/migration/V19__add_transcription_block_versions.sql
new file mode 100644
index 00000000..54df152c
--- /dev/null
+++ b/backend/src/main/resources/db/migration/V19__add_transcription_block_versions.sql
@@ -0,0 +1,9 @@
+CREATE TABLE transcription_block_versions (
+    id         UUID      PRIMARY KEY DEFAULT gen_random_uuid(),
+    block_id   UUID      NOT NULL REFERENCES transcription_blocks(id) ON DELETE CASCADE,
+    text       TEXT      NOT NULL,
+    changed_by UUID      REFERENCES app_users(id) ON DELETE SET NULL,
+    changed_at TIMESTAMP NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_tbv_block ON transcription_block_versions(block_id, changed_at DESC);
diff --git a/backend/src/main/resources/db/migration/V20__add_block_id_to_comments.sql b/backend/src/main/resources/db/migration/V20__add_block_id_to_comments.sql
new file mode 100644
index 00000000..025091ec
--- /dev/null
+++ b/backend/src/main/resources/db/migration/V20__add_block_id_to_comments.sql
@@ -0,0 +1,4 @@
+ALTER TABLE document_comments
+    ADD COLUMN block_id UUID REFERENCES transcription_blocks(id) ON DELETE CASCADE;
+
+CREATE INDEX idx_dc_block ON document_comments(block_id);