diff --git a/server/api/internal/reconcile-payments.post.js b/server/api/internal/reconcile-payments.post.js
index 9c0686f..0fe90ae 100644
--- a/server/api/internal/reconcile-payments.post.js
+++ b/server/api/internal/reconcile-payments.post.js
@@ -65,37 +65,56 @@ export default defineEventHandler(async (event) => {
   let skipped = 0
   let memberErrors = 0
 
-  for (const member of members) {
+  async function processMember(member) {
     let txs
     try {
       txs = await listTransactionsWithRetry(member.helcimCustomerId)
     } catch (err) {
-      memberErrors++
       console.error(`[reconcile] member=${member._id}: ${err?.message || err}`)
-      continue
+      return { error: true }
     }
 
+    const result = { error: false, txExamined: 0, created: 0, existed: 0, skipped: 0 }
+
     for (const tx of txs) {
-      txExamined++
+      result.txExamined++
       if (!RECONCILABLE_STATUSES.has(tx?.status)) {
-        skipped++
+        result.skipped++
         continue
       }
 
       if (!apply) {
         const existing = await Payment.findOne({ helcimTransactionId: tx.id })
-        if (existing) existed++
-        else created++
+        if (existing) result.existed++
+        else result.created++
         continue
       }
 
       // Note: deliberately NOT passing sendConfirmation — cron back-fills must
       // not re-send confirmation emails for transactions the member has already
       // been notified about (or that pre-date Mongo Payment tracking entirely).
-      const result = await upsertPaymentFromHelcim(member, tx)
-      if (result.created) created++
-      else if (result.payment) existed++
-      else skipped++
+      const upsertResult = await upsertPaymentFromHelcim(member, tx)
+      if (upsertResult.created) result.created++
+      else if (upsertResult.payment) result.existed++
+      else result.skipped++
+    }
+
+    return result
+  }
+
+  const CHUNK_SIZE = 8
+  for (let i = 0; i < members.length; i += CHUNK_SIZE) {
+    const chunk = members.slice(i, i + CHUNK_SIZE)
+    const results = await Promise.all(chunk.map((m) => processMember(m)))
+    for (const r of results) {
+      if (r.error) {
+        memberErrors++
+        continue
+      }
+      txExamined += r.txExamined
+      created += r.created
+      existed += r.existed
+      skipped += r.skipped
     }
   }
 
diff --git a/tests/server/api/reconcile-payments-route.test.js b/tests/server/api/reconcile-payments-route.test.js
index 9622153..d8eb78d 100644
--- a/tests/server/api/reconcile-payments-route.test.js
+++ b/tests/server/api/reconcile-payments-route.test.js
@@ -162,12 +162,12 @@ describe('POST /api/internal/reconcile-payments', () => {
       { _id: 'm3', helcimCustomerId: 'cust-3' }
     ]))
     // m1 succeeds first try, m2 fails all 3 retries, m3 succeeds first try.
-    listHelcimCustomerTransactions
-      .mockResolvedValueOnce([{ id: 'tx1', status: 'paid', amount: 5 }])
-      .mockRejectedValueOnce(new Error('helcim 503'))
-      .mockRejectedValueOnce(new Error('helcim 503'))
-      .mockRejectedValueOnce(new Error('helcim 503'))
-      .mockResolvedValueOnce([{ id: 'tx3', status: 'paid', amount: 7 }])
+    // Keyed by customerCode so it works regardless of call order (chunked Promise.all).
+    listHelcimCustomerTransactions.mockImplementation((customerCode) => {
+      if (customerCode === 'cust-1') return Promise.resolve([{ id: 'tx1', status: 'paid', amount: 5 }])
+      if (customerCode === 'cust-3') return Promise.resolve([{ id: 'tx3', status: 'paid', amount: 7 }])
+      return Promise.reject(new Error('helcim 503'))
+    })
     upsertPaymentFromHelcim.mockResolvedValue({ created: true, payment: { _id: 'p' } })
 
     vi.useFakeTimers()