diff --git a/app/backfill-eventId.ts b/app/backfill-eventId.ts
new file mode 100644
index 000000000..8fab012d0
--- /dev/null
+++ b/app/backfill-eventId.ts
@@ -0,0 +1,82 @@
+import { tables } from '@architect/functions'
+import type { DynamoDBDocument } from '@aws-sdk/lib-dynamodb'
+import { paginateScan } from '@aws-sdk/lib-dynamodb'
+
+import {
+  type Circular,
+  parseEventFromSubject,
+} from '~/routes/circulars/circulars.lib'
+
+function* chunks<T>(arr: T[], n: number): Generator<T[], void> {
+  for (let i = 0; i < arr.length; i += n) {
+    yield arr.slice(i, i + n)
+  }
+}
+
+export async function backfill() {
+  // write limit can be adjusted as needed below
+  const writeLimit = 1000
+  const db = await tables()
+  const client = db._doc as unknown as DynamoDBDocument
+  const TableName = db.name('circulars')
+  const pages = paginateScan(
+    { client },
+    {
+      TableName,
+    }
+  )
+  let totalWriteCount = 0
+  let limitHit = false
+
+  console.log(`Starting backfill of ${writeLimit} records...`)
+
+  for await (const page of pages) {
+    if (limitHit) break
+    const chunked = [...chunks(page.Items || [], 25)]
+
+    for (const chunk of chunked) {
+      if (limitHit) break
+      let writes = [] as Circular[]
+
+      for (const record of chunk) {
+        if (limitHit) break
+        const circular = record as unknown as Circular
+        const parsedEventId = parseEventFromSubject(circular.subject)
+
+        if (!circular.eventId && parsedEventId) {
+          circular.eventId = parsedEventId
+          writes.push(circular)
+        }
+
+        // check so we adjust the writes if the write count per
+        // chunk will go over the writeLimit for the run
+        if (writes.length + totalWriteCount > writeLimit) {
+          const overage = writes.length + totalWriteCount - writeLimit
+          const writesToLimitTo = writes.length - overage
+          writes = writes.slice(0, writesToLimitTo)
+          limitHit = true
+        }
+
+        if (writes.length > 0) {
+          await client.batchWrite({
+            RequestItems: {
+              [TableName]: writes.map((circ) => ({
+                PutRequest: {
+                  Item: {
+                    ...circ,
+                  },
+                },
+              })),
+            },
+          })
+        }
+      }
+
+      totalWriteCount = writes.length + totalWriteCount
+    }
+  }
+
+  console.log(
+    `_______Backfill complete. Updated ${totalWriteCount} records.______`
+  )
+}