diff --git a/src/app/api/plan/trigger/route.ts b/src/app/api/plan/trigger/route.ts
index 9746b392..bb18f7c8 100644
--- a/src/app/api/plan/trigger/route.ts
+++ b/src/app/api/plan/trigger/route.ts
@@ -19,6 +19,7 @@ const PresignedUrlBodySchema = z.object({
   already_installed_file_path: z.string().optional(),
   // optional scenario_id to link the plan to an existing scenario
   scenario_id: z.string().optional().nullable(),
+  file_type: z.enum(["csv", "xlsx"]).optional(), // Specify the file type
 });
 
 export async function POST(request: NextRequest) {
@@ -54,8 +55,6 @@ export async function POST(request: NextRequest) {
     console.log("Triggering plan with body: ", validatedBody);
 
     const url = `${process.env.FASTAPI_API_URL}/v1/plan/trigger`;
-    console.log("Triggering plan with url: ", url);
-    console.log("Triggering plan with headers: ", headers);
 
     const response = await fetch(url, {
       method: "POST",
diff --git a/src/app/api/upload/validate/route.ts b/src/app/api/upload/validate/route.ts
index bb69a3b0..8f3526e1 100644
--- a/src/app/api/upload/validate/route.ts
+++ b/src/app/api/upload/validate/route.ts
@@ -10,41 +10,70 @@ export async function POST(req: NextRequest) {
     return NextResponse.json({ error: "No file provided" }, { status: 400 });
   }
 
-  const arrayBuffer = await file.arrayBuffer();
-  const workbook = XLSX.read(arrayBuffer, { type: "array" });
+  const filename = file.name.toLowerCase();
+  const mimeType = file.type;
 
-  const sheetNames = workbook.SheetNames;
+  let fileType: "csv" | "xlsx" | "unknown" = "unknown";
+
+  if (
+    filename.endsWith(".csv") ||
+    mimeType === "text/csv" ||
+    mimeType === "application/vnd.ms-excel"
+  ) {
+    fileType = "csv";
+  } else if (
+    filename.endsWith(".xlsx") ||
+    filename.endsWith(".xls") ||
+    mimeType ===
+      "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
+  ) {
+    fileType = "xlsx";
+  }
+
+  if (fileType === "unknown") {
+    return NextResponse.json(
+      { error: "Unsupported file type", file_type: fileType },
+      { status: 400 }
+    );
+  }
 
   let isStandardised = false;
+  let sheetNames: string[] = [];
 
-  for (const sheetName of sheetNames) {
-    if (sheetName !== "Standardised Asset List") continue;
+  // Handle CSV
+  if (fileType === "csv") {
+    const text = await file.text();
+    const lines = text.split("\n").map((line) => line.split(","));
+    const headers = lines[0].map((h) => h.trim());
+    isStandardised = headers.includes("domna_property_id");
+  }
 
-    const worksheet = workbook.Sheets[sheetName];
-    const jsonData = XLSX.utils.sheet_to_json(worksheet, { header: 1 }) as (
-      | string
-      | number
-      | null
-    )[][];
+  // Handle Excel
+  if (fileType === "xlsx") {
+    const arrayBuffer = await file.arrayBuffer();
 
-    const headers = jsonData.find(
-      (row): row is string[] =>
-        Array.isArray(row) &&
-        row.length > 0 &&
-        row.every((cell) => typeof cell === "string" || cell === null)
-    );
+    // Only load specific sheet to reduce memory usage
+    const workbook = XLSX.read(arrayBuffer, {
+      type: "array",
+      sheets: ["Standardised Asset List"],
+    });
 
-    if (headers?.includes("domna_property_id")) {
-      isStandardised = true;
-      break;
+    sheetNames = workbook.SheetNames;
+
+    const worksheet = workbook.Sheets["Standardised Asset List"];
+    if (worksheet) {
+      const jsonData = XLSX.utils.sheet_to_json(worksheet, { header: 1 });
+      const headers = jsonData[0] as string[];
+      isStandardised = headers?.includes("domna_property_id");
     }
   }
 
   return NextResponse.json({
     message: isStandardised
-      ? "Standardised Asset List format detected. Please select which tab to use."
+      ? "Standardised Asset List format detected."
       : "Valid file. No standardised format detected.",
-    sheetNames: isStandardised ? sheetNames : undefined,
     isStandardised,
+    file_type: fileType,
+    ...(fileType === "xlsx" && isStandardised ? { sheetNames } : {}),
   });
 }
diff --git a/src/app/portfolio/[slug]/components/UploadCsvModal.tsx b/src/app/portfolio/[slug]/components/UploadCsvModal.tsx
index 00c1b01c..bf11fdb7 100644
--- a/src/app/portfolio/[slug]/components/UploadCsvModal.tsx
+++ b/src/app/portfolio/[slug]/components/UploadCsvModal.tsx
@@ -51,9 +51,13 @@ const goalValueOptions = [
   { label: "A", value: "A", disabled: false },
 ];
 
-function generateS3Key(userId: string, portfolioId: string) {
+function generateS3Key(
+  userId: string,
+  portfolioId: string,
+  fileType: "csv" | "xlsx"
+) {
   const timestamp = new Date().toISOString().replace(/[:.-]/g, "");
-  return `${userId}/${portfolioId}/${timestamp}/asset_list.csv`;
+  return `${userId}/${portfolioId}/${timestamp}/asset_list.${fileType}`;
 }
 
 async function uploadCsvToS3({
@@ -103,6 +107,7 @@ export function useUploadCsvPlan({
   ashpCop,
   measures,
   onSuccessRedirect,
+  fileType,
 }: {
   file: File;
   portfolioId: string;
@@ -115,13 +120,14 @@ export function useUploadCsvPlan({
   selectedSheet: string;
   measures: (typeof measuresList)[number][];
   onSuccessRedirect: (path: string) => void;
+  fileType: "csv" | "xlsx";
 }) {
   const session = useSession();
   const userId = String(session.data?.user.dbId);
 
   const fileKey = useMemo(
-    () => generateS3Key(userId, portfolioId),
-    [userId, portfolioId]
+    () => generateS3Key(userId, portfolioId, fileType),
+    [userId, portfolioId, fileType]
   );
 
   const { mutateAsync: uploadFileToS3, isLoading: isUploadLoading } =
@@ -154,6 +160,7 @@ export function useUploadCsvPlan({
         event_type: "remote_assessment",
         sheet_name: selectedSheet,
         ashp_cop: ashpCop,
+        file_type: fileType, // Pass the file type for backend processing
       };
 
       const triggerRes = await fetch("/api/plan/trigger", {
@@ -211,6 +218,7 @@ export default function UploadCsvModal({
   const [csvFile, setCsvFile] = useState<File | null>(null);
   const [selectedScenario, setSelectedScenario] = useState<string | null>(null);
   const [showMeasures, setShowMeasures] = useState(false);
+  const [fileType, setFileType] = useState<"csv" | "xlsx">("csv");
 
   const scenarioOptions = useMemo(
     () =>
@@ -242,6 +250,7 @@ export default function UploadCsvModal({
           setSheetNames([]);
           setSelectedSheet("");
         }
+        setFileType(data.file_type); // capture file type
       },
       onError: () => {
         setSheetNames([]);
@@ -282,6 +291,7 @@ export default function UploadCsvModal({
     ashpCop: form.watch("ashpCop"),
     scenarioName: form.watch("scenario"),
     measures: form.watch("measures"),
+    fileType: fileType,
     portfolioId,
     selectedSheet,
     onSuccessRedirect: (path) => router.push(path),
@@ -496,11 +506,6 @@ export default function UploadCsvModal({
                         />
                       </div>
 
-                      <pre>
-                        {JSON.stringify(form.formState.errors, null, 2)}
-                      </pre>
-                      <pre>{JSON.stringify(form.watch(), null, 2)}</pre>
-
                       <div className="grid grid-cols-2 gap-4">
                         {/* Heat Pump COP */}
                         <FormField