diff --git a/litellm/litellm_core_utils/token_counter.py b/litellm/litellm_core_utils/token_counter.py
index 858b078d626..9ce50cac005 100644
--- a/litellm/litellm_core_utils/token_counter.py
+++ b/litellm/litellm_core_utils/token_counter.py
@@ -695,6 +695,48 @@ def _count_anthropic_content(
     return tokens
 
 
+def _count_file_content_block(count_function: TokenCounterFunction, c: Mapping[str, object]) -> int:
+    """
+    Count an OpenAI file content block (document understanding), e.g.
+    {"type": "file", "file": {"file_id" | "file_data" | "filename", ...}}.
+    The real token cost is the provider's server-side extraction of the
+    document and cannot be derived client-side; counting the base64 file_data
+    blob would wildly overcount. Count only the lightweight textual fields so
+    token_counter/trim_messages accept valid payloads instead of raising
+    (issue #28409).
+    """
+    num_tokens = 0  # rebind-ok: accumulates over the file fields below
+    file_obj: Final = c.get("file")
+    if isinstance(file_obj, dict):
+        for file_field in ("file_id", "filename", "format"):
+            file_field_value = file_obj.get(file_field)
+            if isinstance(file_field_value, str) and file_field_value:
+                num_tokens += count_function(file_field_value)
+    return num_tokens
+
+
+def messages_contain_file_content_blocks(messages: object) -> bool:
+    """
+    True when any message carries an OpenAI ``file`` content block.
+
+    Callers that use ``token_counter`` for reservations or rate limits must
+    check this first: a file block's document payload is opaque to the counter
+    (only the ``file_id``/``filename``/``format`` fields are counted -- see
+    ``_count_file_content_block``), so the count for such a message is a floor,
+    not a measurement, and it must not be trusted as an upper bound.
+    """
+    if not isinstance(messages, list):
+        return False
+    for message in messages:
+        content = message.get("content") if isinstance(message, dict) else None
+        if not isinstance(content, list):
+            continue
+        for content_item in content:
+            if isinstance(content_item, dict) and content_item.get("type") == "file":
+                return True
+    return False
+
+
 def _count_content_list(
     count_function: TokenCounterFunction,
     content_list: OpenAIMessageContent,
@@ -738,11 +780,13 @@ def _count_content_list(
                 tool_name = str(c.get("tool_name") or "")
                 if tool_name:
                     num_tokens += count_function(tool_name)
+            elif c["type"] == "file":
+                num_tokens += _count_file_content_block(count_function, c)
             else:
                 content_type = c.get("type", type(c).__name__) if isinstance(c, dict) else type(c).__name__
                 raise ValueError(
                     f"Invalid content item type: {content_type}. "
-                    f"Expected str or dict with 'type' field (text, image_url, tool_use, tool_result, thinking, tool_reference)."
+                    f"Expected str or dict with 'type' field (text, image_url, tool_use, tool_result, thinking, tool_reference, file)."
                 )
         return num_tokens
     except Exception as e:
diff --git a/litellm/proxy/hooks/batch_rate_limiter.py b/litellm/proxy/hooks/batch_rate_limiter.py
index 5b814ad28fd..8672580e194 100644
--- a/litellm/proxy/hooks/batch_rate_limiter.py
+++ b/litellm/proxy/hooks/batch_rate_limiter.py
@@ -35,6 +35,7 @@ from litellm.batches.batch_utils import (
 )
 from litellm.exceptions import RateLimitErrorCategory
 from litellm.integrations.custom_logger import CustomLogger
+from litellm.litellm_core_utils.token_counter import messages_contain_file_content_blocks
 from litellm.proxy._types import (
     ProxyErrorTypes,
     ProxyException,
@@ -853,6 +854,15 @@ class _PROXY_BatchRateLimiter(CustomLogger):
 
                 try:
                     entry_total_tokens = _count_entry_tokens(entry)
+                    # A `file` content block's document payload is opaque to
+                    # token_counter -- only its filename/id fields are counted
+                    # (see token_counter._count_file_content_block) -- so a row
+                    # carrying a large base64 `file_data` would count as a few
+                    # tokens and slide the whole batch under the TPM limit.
+                    # Floor such rows at the size-based estimate, which does
+                    # cover the payload bytes.
+                    if messages_contain_file_content_blocks((entry.get("body") or {}).get("messages")):
+                        entry_total_tokens = max(entry_total_tokens, _estimate_batch_entry_tokens(raw_line))
                 except Exception:
                     entry_total_tokens = _estimate_batch_entry_tokens(raw_line)
                 total_tokens += entry_total_tokens
diff --git a/litellm/proxy/spend_tracking/budget_reservation.py b/litellm/proxy/spend_tracking/budget_reservation.py
index 7cad3f0a022..a755b1c1a76 100644
--- a/litellm/proxy/spend_tracking/budget_reservation.py
+++ b/litellm/proxy/spend_tracking/budget_reservation.py
@@ -15,6 +15,7 @@ from litellm._logging import verbose_proxy_logger
 from litellm.caching import DualCache
 from litellm.litellm_core_utils.duration_parser import duration_in_seconds
 from litellm.litellm_core_utils.llm_cost_calc.tiered_pricing import select_tier_for_input, tier_rate
+from litellm.litellm_core_utils.token_counter import messages_contain_file_content_blocks
 from litellm.proxy._types import (
     Litellm_EntityType,
     LiteLLM_TeamMembership,
@@ -1279,9 +1280,20 @@ def _approximate_input_size(request_body: Mapping[str, object]) -> int:
 def _count_input_tokens(request_body: dict, model: str) -> int | None:
     try:
         if "messages" in request_body:
+            messages: Final = request_body.get("messages") or []
+            # A `file` content block's real token cost is the provider's
+            # server-side extraction of the referenced document and cannot be
+            # derived client-side — token_counter only counts its filename/id
+            # fields, which would under-reserve arbitrarily large uploads.
+            # Return None so the caller takes the conservative max_input_tokens
+            # reservation — an explicit return, because falling through would
+            # let a stray `prompt` / `input` / `query` on the same body count
+            # as the whole request.
+            if messages_contain_file_content_blocks(messages):
+                return None
             return litellm.token_counter(
                 model=model,
-                messages=request_body.get("messages") or [],
+                messages=messages,
                 tools=request_body.get("tools"),
                 tool_choice=request_body.get("tool_choice"),
             )
diff --git a/tests/test_litellm/litellm_core_utils/test_token_counter.py b/tests/test_litellm/litellm_core_utils/test_token_counter.py
index a2590dbca2d..e116c39edcc 100644
--- a/tests/test_litellm/litellm_core_utils/test_token_counter.py
+++ b/tests/test_litellm/litellm_core_utils/test_token_counter.py
@@ -1160,3 +1160,90 @@ def test_count_content_list_rejects_unknown_type():
     message = str(exc_info.value)
     assert "Invalid content item type: totally_unknown_block" in message
     assert "tool_reference" in message
+    assert "file" in message
+
+
+def test_token_counter_with_file_content_block():
+    """
+    Regression test for issue #28409: a message containing an OpenAI `file`
+    content block (document understanding) must NOT raise from token_counter
+    or trim_messages.
+
+    The real token cost of a file is the provider's server-side extraction and
+    cannot be derived client-side; only the lightweight textual fields
+    (file_id / filename / format) are counted — the opaque base64 `file_data`
+    blob must not inflate the count.
+    """
+    messages = [
+        {
+            "role": "user",
+            "content": [
+                {"type": "text", "text": "Summarize this document."},
+                {
+                    "type": "file",
+                    "file": {
+                        "file_id": "file-abc123",
+                        "filename": "report.pdf",
+                        "format": "application/pdf",
+                    },
+                },
+            ],
+        }
+    ]
+
+    tokens = token_counter_new(model="gpt-4o", messages=messages)
+    assert tokens > 0, f"Expected positive token count, got {tokens}"
+
+    # base64 file_data is opaque — it must not blow up the count
+    small_blob = dict(messages[0]["content"][1]["file"], file_data="data:application/pdf;base64,AAAA")
+    big_blob = dict(messages[0]["content"][1]["file"], file_data="data:application/pdf;base64," + "A" * 100_000)
+    tokens_small = token_counter_new(
+        model="gpt-4o",
+        messages=[{"role": "user", "content": [{"type": "file", "file": small_blob}]}],
+    )
+    tokens_big = token_counter_new(
+        model="gpt-4o",
+        messages=[{"role": "user", "content": [{"type": "file", "file": big_blob}]}],
+    )
+    assert tokens_small == tokens_big, "opaque file_data blob must not be counted"
+
+    # a bare file block (e.g. only file_data) must also not raise
+    tokens_bare = token_counter_new(
+        model="gpt-4o",
+        messages=[
+            {
+                "role": "user",
+                "content": [{"type": "file", "file": {"file_data": "data:application/pdf;base64,AAAA"}}],
+            }
+        ],
+    )
+    assert tokens_bare >= 0
+
+
+def test_trim_messages_with_file_content_block():
+    """The original repro from issue #28409: trim_messages on a document
+    understanding payload raised ValueError from token_counter (1.83.14) —
+    current versions swallow that error and silently return the messages
+    UNTRIMMED instead. With the fix, trimming must actually happen."""
+    messages = [
+        {"role": "user", "content": "filler message " * 200},
+        {"role": "user", "content": "filler message " * 200},
+        {
+            "role": "user",
+            "content": [
+                {"type": "text", "text": "What is in this file?"},
+                {
+                    "type": "file",
+                    "file": {"file_id": "file-abc123", "filename": "report.pdf"},
+                },
+            ],
+        },
+    ]
+
+    trimmed = litellm.utils.trim_messages(messages, model="gpt-4o", max_tokens=120)
+
+    assert trimmed is not None
+    assert len(trimmed) < len(messages), (
+        "trim_messages must actually trim an over-budget conversation containing "
+        f"a file content block — got {len(trimmed)} messages back (input {len(messages)})"
+    )
diff --git a/tests/test_litellm/proxy/hooks/test_batch_file_validation.py b/tests/test_litellm/proxy/hooks/test_batch_file_validation.py
index 4ef94f0965b..09f468d1f5c 100644
--- a/tests/test_litellm/proxy/hooks/test_batch_file_validation.py
+++ b/tests/test_litellm/proxy/hooks/test_batch_file_validation.py
@@ -1827,6 +1827,105 @@ async def test_count_input_file_usage_streams_without_building_list():
     mock_dict_list.assert_not_called()
 
 
+@pytest.mark.asyncio
+async def test_file_content_block_row_reserves_size_based_floor():
+    """A chat row carrying an OpenAI `file` content block must reserve at
+    least the size-based estimate (serialized bytes / 4).
+
+    token_counter deliberately counts only the block's filename/id fields —
+    the document payload is opaque to it — so without this floor a row
+    carrying a large base64 `file_data` counts as a handful of tokens and the
+    whole batch slides under the TPM limit. Before file blocks were countable
+    (#33659) such a row RAISED inside token_counter and fell back to the
+    size-based estimate; the floor restores exactly that conservatism.
+    """
+    import json as _json
+
+    from litellm.proxy.hooks.batch_rate_limiter import _PROXY_BatchRateLimiter
+
+    prl = MagicMock()
+    prl.no_max_tokens_output_floor.return_value = 0
+    rate_limiter = _PROXY_BatchRateLimiter(
+        internal_usage_cache=MagicMock(),
+        parallel_request_limiter=prl,
+    )
+
+    blob = "data:application/pdf;base64," + "A" * 400_000
+    file_row_bytes = _json.dumps(
+        {
+            "custom_id": "row-1",
+            "method": "POST",
+            "url": "/v1/chat/completions",
+            "body": {
+                "model": "gpt-4o-mini",
+                "messages": [
+                    {
+                        "role": "user",
+                        "content": [
+                            {"type": "text", "text": "Summarize this document."},
+                            {
+                                "type": "file",
+                                "file": {"filename": "report.pdf", "file_data": blob},
+                            },
+                        ],
+                    }
+                ],
+            },
+        }
+    ).encode("utf-8")
+    fake_content = MagicMock()
+    fake_content.content = file_row_bytes
+
+    with patch(  # test-quality-ok: mirrors the file's established harness — the download, not an HTTP boundary
+        "litellm.afile_content",
+        new=AsyncMock(return_value=fake_content),
+    ):
+        usage = await rate_limiter.count_input_file_usage(
+            file_id="file-not-managed",
+            custom_llm_provider="openai",
+            user_api_key_dict=None,
+        )
+
+    size_based_floor = len(file_row_bytes) // 4
+    assert usage.request_count == 1
+    assert usage.total_tokens >= size_based_floor, (
+        f"file-block row must reserve at least the size-based estimate "
+        f"({size_based_floor} tokens for {len(file_row_bytes)} bytes), got "
+        f"{usage.total_tokens} — a large file_data payload would evade TPM limits"
+    )
+
+    # Control: a plain-text row must NOT be floored at its serialized size —
+    # measured text rows keep the (smaller) real token count.
+    text_row_bytes = _json.dumps(
+        {
+            "custom_id": "row-1",
+            "method": "POST",
+            "url": "/v1/chat/completions",
+            "body": {
+                "model": "gpt-4o-mini",
+                "messages": [{"role": "user", "content": "Summarize this document."}],
+            },
+        }
+    ).encode("utf-8")
+    fake_text_content = MagicMock()
+    fake_text_content.content = text_row_bytes
+
+    with patch(  # test-quality-ok: mirrors the file's established harness — the download, not an HTTP boundary
+        "litellm.afile_content",
+        new=AsyncMock(return_value=fake_text_content),
+    ):
+        text_usage = await rate_limiter.count_input_file_usage(
+            file_id="file-not-managed",
+            custom_llm_provider="openai",
+            user_api_key_dict=None,
+        )
+
+    assert 0 < text_usage.total_tokens < len(text_row_bytes) // 4, (
+        "plain-text rows must keep the measured token count, not the size floor "
+        f"— got {text_usage.total_tokens} for a {len(text_row_bytes)}-byte row"
+    )
+
+
 def _one_row_batch_bytes(model: str) -> bytes:
     import json as _json
 
diff --git a/tests/test_litellm/proxy/test_budget_reservation.py b/tests/test_litellm/proxy/test_budget_reservation.py
index 38a346e7fb7..e2677363c5d 100644
--- a/tests/test_litellm/proxy/test_budget_reservation.py
+++ b/tests/test_litellm/proxy/test_budget_reservation.py
@@ -1115,6 +1115,56 @@ def test_reservation_uses_most_expensive_deployment_in_group():
     assert estimated == pytest.approx(expected_expensive)
 
 
+def test_estimate_input_tokens_reserves_max_for_file_content_blocks():
+    """A `file` content block's real token cost is the provider's server-side
+    extraction of the referenced document — token_counter only sees the
+    filename/id, so counting it would under-reserve arbitrarily large uploads.
+    Reservation must fall back to the conservative max_input_tokens instead."""
+    from litellm.proxy.spend_tracking.budget_reservation import (
+        _estimate_input_tokens,
+    )
+
+    file_request = {
+        "messages": [
+            {
+                "role": "user",
+                "content": [
+                    {"type": "text", "text": "Summarize this document."},
+                    {"type": "file", "file": {"file_id": "file-abc123"}},
+                ],
+            }
+        ]
+    }
+    estimated = _estimate_input_tokens(
+        request_body=file_request,
+        route="/chat/completions",
+        model="gpt-4o",
+        model_info={"max_input_tokens": 128000},
+    )
+    assert estimated == 128000
+
+    # A stray text field on the same body must not be counted in place of the
+    # file — the messages branch owns the request once `messages` is present.
+    decoy_request = {**file_request, "prompt": "hi"}
+    decoy_estimated = _estimate_input_tokens(
+        request_body=decoy_request,
+        route="/chat/completions",
+        model="gpt-4o",
+        model_info={"max_input_tokens": 128000},
+    )
+    assert decoy_estimated == 128000
+
+    # Plain text messages must still be counted, not blanket-reserved.
+    text_request = {"messages": [{"role": "user", "content": "hi"}]}
+    counted = _estimate_input_tokens(
+        request_body=text_request,
+        route="/chat/completions",
+        model="gpt-4o",
+        model_info={"max_input_tokens": 128000},
+    )
+    assert counted is not None and 0 < counted < 128000
+
+
 @pytest.mark.asyncio
 async def test_should_clamp_reservation_to_model_ceiling_when_caller_overrequests(
     spend_counter_state,