diff --git a/scripts/workers/fax_sender.py b/scripts/workers/fax_sender.py
index d0f4b1b..70cbafc 100644
--- a/scripts/workers/fax_sender.py
+++ b/scripts/workers/fax_sender.py
@@ -63,6 +63,12 @@ async def send_fax(
     Returns:
         dict with keys: success, log_id, device, status, error
     """
+    # Guard: don't fax in dev/test
+    is_prod = os.getenv("NODE_ENV") == "production" or os.getenv("ENV") == "production"
+    if not is_prod:
+        LOG.info("[fax] DEV MODE — skipping fax to %s", recipient)
+        return {"success": True, "log_id": "dev-skip", "device": "dev", "status": "skipped", "error": None}
+
     url = f"https://{PBX_HOST}/api/v2/virtual_faxes/{PBX_FAX_ID}/send"
     headers = {
         "app-key": PBX_API_KEY,
diff --git a/scripts/workers/services/fmcsa_web_submitter.py b/scripts/workers/services/fmcsa_web_submitter.py
index 0b8cd7a..8c88a80 100644
--- a/scripts/workers/services/fmcsa_web_submitter.py
+++ b/scripts/workers/services/fmcsa_web_submitter.py
@@ -64,6 +64,19 @@ async def submit_mcs150(
 
     submitted_at = datetime.now(timezone.utc)
 
+    # Guard: don't submit to FMCSA in dev/test
+    is_prod = os.getenv("NODE_ENV") == "production" or os.getenv("ENV") == "production"
+    if not is_prod:
+        LOG.info("[fmcsa] DEV MODE — skipping web submission for DOT %s", dot_number)
+        return {
+            "success": True,
+            "screenshot_path": None,
+            "pre_submit_screenshot": None,
+            "submitted_at": submitted_at.isoformat(),
+            "confirmation_text": "DEV MODE — submission skipped",
+            "error": None,
+        }
+
     try:
         from patchright.async_api import async_playwright
     except ImportError:
diff --git a/scripts/workers/services/mcs150_update.py b/scripts/workers/services/mcs150_update.py
index 2a787fa..bd84eaf 100644
--- a/scripts/workers/services/mcs150_update.py
+++ b/scripts/workers/services/mcs150_update.py
@@ -186,8 +186,21 @@ class MCS150UpdateHandler:
                 LOG.error("[%s] E-sign setup failed (proceeding anyway): %s", order_number, exc)
 
         # Step 5: Submit electronically (3x web → fax fallback)
+        # GUARD: Skip actual submission in dev/test environments
+        is_production = os.environ.get("NODE_ENV") == "production" or os.environ.get("ENV") == "production"
         filing_result = None
-        if pdf_path:
+        if pdf_path and not is_production:
+            LOG.info("[%s] DEV MODE — skipping actual FMCSA submission", order_number)
+            filing_result = {
+                "success": True,
+                "method": "dev_skip",
+                "attested_pdf": None,
+                "submitted_at": datetime.now().isoformat(),
+                "screenshot_path": None,
+                "fax_log_id": None,
+                "error": None,
+            }
+        elif pdf_path:
             try:
                 import asyncio
                 from scripts.workers.fax_sender import submit_filing