diff --git a/src/routes/invoices.$invoiceId.tsx b/src/routes/invoices.$invoiceId.tsx
index 535eaae..d71eded 100644
--- a/src/routes/invoices.$invoiceId.tsx
+++ b/src/routes/invoices.$invoiceId.tsx
@@ -130,6 +130,19 @@ function InvoiceDetail() {
   const isDraft = invoice.status === "draft";
   const balance = Number(invoice.total) - Number(invoice.amount_paid);
 
+  // Billable fees vs billable expenses subtotals (non-billable items have amount 0 and are excluded).
+  const { feesSubtotal, expensesSubtotal } = useMemo(() => {
+    let fees = 0;
+    let exp = 0;
+    for (const it of items) {
+      const amt = Number(it.amount) || 0;
+      if (amt === 0) continue;
+      if (it.kind === "expense") exp += amt;
+      else fees += amt;
+    }
+    return { feesSubtotal: fees, expensesSubtotal: exp };
+  }, [items]);
+
   const setStatus = async (status: string) => {
     if (status === "void") {
       if (!confirm("Void this invoice? Totals will be zeroed out and time/expenses will be unbilled.")) return;