diff --git a/app/models/position.py b/app/models/position.py
index 3ae20c8..10062e0 100644
--- a/app/models/position.py
+++ b/app/models/position.py
@@ -22,6 +22,9 @@ class Position:
         entry_date: Date of position entry (for historical conversion lookups)
         entry_basis_mode: Entry basis mode ("weight" or "value_price")
         notes: Optional notes about this position
+        storage_cost_basis: Annual storage cost as percentage (e.g., Decimal("0.12") for 0.12%) or fixed amount
+        storage_cost_period: Period for storage cost ("annual" or "monthly")
+        storage_cost_currency: Currency for fixed amount costs (default "USD")
         created_at: Timestamp when position was created
     """
 
@@ -33,6 +36,9 @@ class Position:
     entry_date: date
     entry_basis_mode: str = "weight"
     notes: str = ""
+    storage_cost_basis: Decimal | None = None
+    storage_cost_period: str | None = None
+    storage_cost_currency: str = "USD"
     created_at: datetime = field(default_factory=lambda: datetime.now(UTC))
 
     def __post_init__(self) -> None:
@@ -67,6 +73,9 @@ class Position:
             "entry_date": self.entry_date.isoformat(),
             "entry_basis_mode": self.entry_basis_mode,
             "notes": self.notes,
+            "storage_cost_basis": str(self.storage_cost_basis) if self.storage_cost_basis is not None else None,
+            "storage_cost_period": self.storage_cost_period,
+            "storage_cost_currency": self.storage_cost_currency,
             "created_at": self.created_at.isoformat(),
         }
 
@@ -82,6 +91,11 @@ class Position:
             entry_date=date.fromisoformat(data["entry_date"]),
             entry_basis_mode=data.get("entry_basis_mode", "weight"),
             notes=data.get("notes", ""),
+            storage_cost_basis=(
+                Decimal(data["storage_cost_basis"]) if data.get("storage_cost_basis") is not None else None
+            ),
+            storage_cost_period=data.get("storage_cost_period"),
+            storage_cost_currency=data.get("storage_cost_currency", "USD"),
             created_at=datetime.fromisoformat(data["created_at"]) if "created_at" in data else datetime.now(UTC),
         )
 
@@ -94,6 +108,9 @@ def create_position(
     entry_date: date | None = None,
     entry_basis_mode: str = "weight",
     notes: str = "",
+    storage_cost_basis: Decimal | None = None,
+    storage_cost_period: str | None = None,
+    storage_cost_currency: str = "USD",
 ) -> Position:
     """Create a new position with sensible defaults.
 
@@ -105,6 +122,9 @@ def create_position(
         entry_date: Entry date (default: today)
         entry_basis_mode: Entry basis mode (default: "weight")
         notes: Optional notes
+        storage_cost_basis: Annual storage cost as percentage or fixed amount (default: None)
+        storage_cost_period: Period for storage cost ("annual" or "monthly", default: None)
+        storage_cost_currency: Currency for fixed amount costs (default: "USD")
     """
     return Position(
         id=uuid4(),
@@ -115,4 +135,7 @@ def create_position(
         entry_date=entry_date or date.today(),
         entry_basis_mode=entry_basis_mode,
         notes=notes,
+        storage_cost_basis=storage_cost_basis,
+        storage_cost_period=storage_cost_period,
+        storage_cost_currency=storage_cost_currency,
     )
diff --git a/app/pages/overview.py b/app/pages/overview.py
index 683fd20..926bda0 100644
--- a/app/pages/overview.py
+++ b/app/pages/overview.py
@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import logging
 from datetime import datetime, timezone
+from decimal import Decimal
 
 from fastapi import Request
 from fastapi.responses import RedirectResponse
@@ -21,6 +22,7 @@ from app.pages.common import (
 from app.services.alerts import AlertService, build_portfolio_alert_context
 from app.services.ltv_history import LtvHistoryChartModel, LtvHistoryService
 from app.services.runtime import get_data_service
+from app.services.storage_costs import calculate_total_storage_cost
 from app.services.turnstile import load_turnstile_settings
 
 logger = logging.getLogger(__name__)
@@ -163,6 +165,17 @@ async def overview_page(workspace_id: str) -> None:
     configured_gold_value = float(config.gold_value or 0.0)
     portfolio["cash_buffer"] = max(float(portfolio["gold_value"]) - configured_gold_value, 0.0) + _DEFAULT_CASH_BUFFER
     portfolio["hedge_budget"] = float(config.monthly_budget)
+
+    # Calculate storage costs for positions
+    positions = config.positions
+    current_values: dict[str, Decimal] = {}
+    for pos in positions:
+        # Use entry value as proxy for current value (would need live prices for accurate calc)
+        current_values[str(pos.id)] = pos.entry_value
+    total_annual_storage_cost = calculate_total_storage_cost(positions, current_values)
+    portfolio["annual_storage_cost"] = float(total_annual_storage_cost)
+    portfolio["storage_cost_pct"] = (float(total_annual_storage_cost) / float(portfolio["gold_value"]) * 100) if portfolio["gold_value"] > 0 else 0.0
+
     alert_status = AlertService().evaluate(config, portfolio)
     ltv_history_service = LtvHistoryService(repository=LtvHistoryRepository(base_path=repo.base_path))
     ltv_history_notice: str | None = None
@@ -362,6 +375,11 @@ async def overview_page(workspace_id: str) -> None:
                             f"${portfolio['hedge_budget']:,.0f}",
                             "Monthly budget from saved settings",
                         ),
+                        (
+                            "Storage Costs",
+                            f"${portfolio['annual_storage_cost']:,.2f}/yr ({portfolio['storage_cost_pct']:.2f}%)",
+                            "Annual vault storage for physical positions (GLD expense ratio baked into share price)",
+                        ),
                     ]
                     for title, value, caption in summary_cards:
                         with ui.card().classes(
diff --git a/app/pages/settings.py b/app/pages/settings.py
index 61984e4..d6d3b46 100644
--- a/app/pages/settings.py
+++ b/app/pages/settings.py
@@ -15,6 +15,7 @@ from app.models.workspace import get_workspace_repository
 from app.pages.common import dashboard_page, split_page_panes
 from app.services.alerts import AlertService, build_portfolio_alert_context
 from app.services.settings_status import save_status_text
+from app.services.storage_costs import get_default_storage_cost_for_underlying
 
 logger = logging.getLogger(__name__)
 
@@ -334,6 +335,19 @@ def settings_page(workspace_id: str) -> None:
                         label="Underlying",
                     ).classes("w-full")
 
+                    def update_storage_cost_default() -> None:
+                        """Update storage cost defaults based on underlying selection."""
+                        underlying = str(pos_underlying.value)
+                        default_basis, default_period = get_default_storage_cost_for_underlying(underlying)
+                        if default_basis is not None:
+                            pos_storage_cost_basis.value = float(default_basis)
+                            pos_storage_cost_period.value = default_period or "annual"
+                        else:
+                            pos_storage_cost_basis.value = 0.0
+                            pos_storage_cost_period.value = "annual"
+
+                    pos_underlying.on_value_change(lambda _: update_storage_cost_default())
+
                     pos_quantity = ui.number(
                         "Quantity",
                         value=100.0,
@@ -369,6 +383,23 @@ def settings_page(workspace_id: str) -> None:
                         placeholder="Add notes about this position...",
                     ).classes("w-full")
 
+                    ui.separator().classes("my-3")
+                    ui.label("Storage Costs (optional)").classes("text-sm font-semibold text-slate-700 dark:text-slate-300")
+                    ui.label("For physical gold (XAU), defaults to 0.12% annual vault storage.").classes("text-xs text-slate-500 dark:text-slate-400 mb-2")
+
+                    pos_storage_cost_basis = ui.number(
+                        "Storage cost (% per year or fixed $)",
+                        value=0.0,
+                        min=0.0,
+                        step=0.01,
+                    ).classes("w-full")
+
+                    pos_storage_cost_period = ui.select(
+                        {"annual": "Annual", "monthly": "Monthly"},
+                        value="annual",
+                        label="Cost period",
+                    ).classes("w-full")
+
                     with ui.row().classes("w-full gap-3 mt-4"):
                         ui.button("Cancel", on_click=lambda: add_position_dialog.close()).props("outline")
                         ui.button("Add Position", on_click=lambda: add_position_from_form()).props("color=primary")
@@ -376,15 +407,22 @@ def settings_page(workspace_id: str) -> None:
                 def add_position_from_form() -> None:
                     """Add a new position from the form."""
                     try:
+                        underlying = str(pos_underlying.value)
+                        storage_cost_basis_val = float(pos_storage_cost_basis.value)
+                        storage_cost_basis = Decimal(str(storage_cost_basis_val)) if storage_cost_basis_val > 0 else None
+                        storage_cost_period = str(pos_storage_cost_period.value) if storage_cost_basis else None
+
                         new_position = Position(
                             id=uuid4(),
-                            underlying=str(pos_underlying.value),
+                            underlying=underlying,
                             quantity=Decimal(str(pos_quantity.value)),
                             unit=str(pos_unit.value),
                             entry_price=Decimal(str(pos_entry_price.value)),
                             entry_date=date.fromisoformat(str(pos_entry_date.value)),
                             entry_basis_mode="weight",
                             notes=str(pos_notes.value or ""),
+                            storage_cost_basis=storage_cost_basis,
+                            storage_cost_period=storage_cost_period,
                         )
                         workspace_repo.add_position(workspace_id, new_position)
                         add_position_dialog.close()
@@ -423,6 +461,19 @@ def settings_page(workspace_id: str) -> None:
                                     ui.label(f"Value: ${float(pos.entry_value):,.2f}").classes(
                                         "text-xs font-semibold text-emerald-600 dark:text-emerald-400"
                                     )
+                                    # Show storage cost if configured
+                                    if pos.storage_cost_basis is not None:
+                                        basis_val = float(pos.storage_cost_basis)
+                                        period = pos.storage_cost_period or "annual"
+                                        if basis_val < 1:
+                                            # Percentage
+                                            storage_label = f"{basis_val:.2f}% {period} storage"
+                                        else:
+                                            # Fixed amount
+                                            storage_label = f"${basis_val:,.2f} {period} storage"
+                                        ui.label(f"Storage: {storage_label}").classes(
+                                            "text-xs text-slate-500 dark:text-slate-400"
+                                        )
                                 with ui.row().classes("gap-1"):
                                     ui.button(
                                         icon="delete",
diff --git a/app/services/storage_costs.py b/app/services/storage_costs.py
new file mode 100644
index 0000000..2ec8106
--- /dev/null
+++ b/app/services/storage_costs.py
@@ -0,0 +1,105 @@
+"""Storage cost calculation service for positions with physical storage requirements."""
+
+from __future__ import annotations
+
+from decimal import Decimal
+
+from app.models.position import Position
+
+_DECIMAL_ZERO = Decimal("0")
+_DECIMAL_ONE = Decimal("1")
+_DECIMAL_HUNDRED = Decimal("100")
+_DECIMAL_TWELVE = Decimal("12")
+
+
+def calculate_annual_storage_cost(position: Position, current_value: Decimal) -> Decimal:
+    """Calculate annual storage cost for a single position.
+
+    Args:
+        position: Position with optional storage_cost_basis and storage_cost_period
+        current_value: Current market value of the position (quantity × current_price)
+
+    Returns:
+        Annual storage cost in position's storage_cost_currency (default USD)
+
+    Notes:
+        - If storage_cost_basis is None, returns 0 (no storage cost)
+        - If storage_cost_period is "monthly", annualizes the cost (×12)
+        - If storage_cost_basis is a percentage, applies it to current_value
+        - If storage_cost_basis is a fixed amount, uses it directly
+    """
+    if position.storage_cost_basis is None:
+        return _DECIMAL_ZERO
+
+    basis = position.storage_cost_basis
+    period = position.storage_cost_period or "annual"
+
+    # Determine if basis is a percentage (e.g., 0.12 for 0.12%) or fixed amount
+    # Heuristic: if basis < 1, treat as percentage; otherwise as fixed amount
+    if basis < _DECIMAL_ONE:
+        # Percentage-based cost
+        if period == "monthly":
+            # Monthly percentage, annualize it
+            annual_rate = basis * _DECIMAL_TWELVE
+        else:
+            # Already annual
+            annual_rate = basis
+
+        # Apply percentage to current value
+        return (current_value * annual_rate) / _DECIMAL_HUNDRED
+    else:
+        # Fixed amount
+        if period == "monthly":
+            # Monthly fixed cost, annualize it
+            return basis * _DECIMAL_TWELVE
+        else:
+            # Already annual fixed cost
+            return basis
+
+
+def calculate_total_storage_cost(
+    positions: list[Position],
+    current_values: dict[str, Decimal],
+) -> Decimal:
+    """Calculate total annual storage cost across all positions.
+
+    Args:
+        positions: List of positions with optional storage costs
+        current_values: Mapping of position ID (str) to current market value
+
+    Returns:
+        Total annual storage cost in USD (assumes all positions use USD)
+    """
+    total = _DECIMAL_ZERO
+    for position in positions:
+        current_value = current_values.get(str(position.id), _DECIMAL_ZERO)
+        cost = calculate_annual_storage_cost(position, current_value)
+        total += cost
+    return total
+
+
+def get_default_storage_cost_for_underlying(underlying: str) -> tuple[Decimal | None, str | None]:
+    """Get default storage cost settings for a given underlying instrument.
+
+    Args:
+        underlying: Instrument symbol (e.g., "XAU", "GLD", "GC=F")
+
+    Returns:
+        Tuple of (storage_cost_basis, storage_cost_period) or (None, None) if no default
+
+    Notes:
+        - XAU (physical gold): 0.12% annual for allocated vault storage
+        - GLD: None (expense ratio baked into share price)
+        - GC=F: None (roll costs are the storage analog, handled separately)
+    """
+    if underlying == "XAU":
+        # Physical gold: 0.12% annual storage cost for allocated vault storage
+        return Decimal("0.12"), "annual"
+    elif underlying == "GLD":
+        # GLD: expense ratio is implicit in share price, no separate storage cost
+        return None, None
+    elif underlying == "GC=F":
+        # Futures: roll costs are the storage analog (deferred to GCF-001)
+        return None, None
+    else:
+        return None, None
diff --git a/tests/test_storage_costs.py b/tests/test_storage_costs.py
new file mode 100644
index 0000000..c3d15e1
--- /dev/null
+++ b/tests/test_storage_costs.py
@@ -0,0 +1,303 @@
+"""Tests for storage cost calculations."""
+
+from __future__ import annotations
+
+from decimal import Decimal
+from uuid import uuid4
+
+from app.models.position import Position, create_position
+from app.services.storage_costs import (
+    calculate_annual_storage_cost,
+    calculate_total_storage_cost,
+    get_default_storage_cost_for_underlying,
+)
+
+
+class TestCalculateAnnualStorageCost:
+    """Test calculate_annual_storage_cost function."""
+
+    def test_no_storage_cost_returns_zero(self) -> None:
+        """Test that position without storage cost returns zero."""
+        pos = create_position(
+            underlying="GLD",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=None,
+        )
+        current_value = Decimal("215000")
+
+        result = calculate_annual_storage_cost(pos, current_value)
+
+        assert result == Decimal("0")
+
+    def test_percentage_annual_cost(self) -> None:
+        """Test percentage-based annual storage cost."""
+        pos = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("0.12"),  # 0.12%
+            storage_cost_period="annual",
+        )
+        current_value = Decimal("215000")
+
+        result = calculate_annual_storage_cost(pos, current_value)
+
+        # 0.12% of 215000 = 258
+        expected = Decimal("258")
+        assert result == expected
+
+    def test_percentage_monthly_cost_annualized(self) -> None:
+        """Test percentage-based monthly storage cost is annualized."""
+        pos = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("0.01"),  # 0.01% per month
+            storage_cost_period="monthly",
+        )
+        current_value = Decimal("215000")
+
+        result = calculate_annual_storage_cost(pos, current_value)
+
+        # 0.01% monthly × 12 = 0.12% annual
+        # 0.12% of 215000 = 258
+        expected = Decimal("258")
+        assert result == expected
+
+    def test_fixed_annual_cost(self) -> None:
+        """Test fixed annual storage cost."""
+        pos = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("300"),  # $300 per year
+            storage_cost_period="annual",
+        )
+        current_value = Decimal("215000")
+
+        result = calculate_annual_storage_cost(pos, current_value)
+
+        assert result == Decimal("300")
+
+    def test_fixed_monthly_cost_annualized(self) -> None:
+        """Test fixed monthly storage cost is annualized."""
+        pos = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("25"),  # $25 per month
+            storage_cost_period="monthly",
+        )
+        current_value = Decimal("215000")
+
+        result = calculate_annual_storage_cost(pos, current_value)
+
+        # $25 × 12 = $300 per year
+        expected = Decimal("300")
+        assert result == expected
+
+    def test_percentage_boundary_at_one(self) -> None:
+        """Test that basis < 1 is treated as percentage, >= 1 as fixed."""
+        # 0.99 should be treated as percentage
+        pos_pct = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("0.99"),
+            storage_cost_period="annual",
+        )
+        current_value = Decimal("100000")
+        result_pct = calculate_annual_storage_cost(pos_pct, current_value)
+        # 0.99% of 100000 = 990
+        assert result_pct == Decimal("990")
+
+        # 1.00 should be treated as fixed
+        pos_fixed = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("1"),
+            storage_cost_period="annual",
+        )
+        result_fixed = calculate_annual_storage_cost(pos_fixed, current_value)
+        assert result_fixed == Decimal("1")
+
+
+class TestCalculateTotalStorageCost:
+    """Test calculate_total_storage_cost function."""
+
+    def test_empty_positions_returns_zero(self) -> None:
+        """Test that empty position list returns zero."""
+        result = calculate_total_storage_cost([], {})
+        assert result == Decimal("0")
+
+    def test_multiple_positions_summed(self) -> None:
+        """Test that multiple positions have costs summed."""
+        pos1 = create_position(
+            underlying="XAU",
+            quantity=Decimal("50"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("0.12"),
+            storage_cost_period="annual",
+        )
+        pos2 = create_position(
+            underlying="XAU",
+            quantity=Decimal("50"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("0.12"),
+            storage_cost_period="annual",
+        )
+        positions = [pos1, pos2]
+        current_values = {
+            str(pos1.id): Decimal("107500"),  # 50 × 2150
+            str(pos2.id): Decimal("107500"),
+        }
+
+        result = calculate_total_storage_cost(positions, current_values)
+
+        # Each: 0.12% of 107500 = 129
+        # Total: 129 + 129 = 258
+        expected = Decimal("258")
+        assert result == expected
+
+    def test_mixed_positions_with_and_without_costs(self) -> None:
+        """Test positions with and without storage costs."""
+        pos_xau = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("0.12"),
+            storage_cost_period="annual",
+        )
+        pos_gld = create_position(
+            underlying="GLD",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=None,  # GLD has no storage cost
+        )
+        positions = [pos_xau, pos_gld]
+        current_values = {
+            str(pos_xau.id): Decimal("215000"),
+            str(pos_gld.id): Decimal("215000"),
+        }
+
+        result = calculate_total_storage_cost(positions, current_values)
+
+        # Only XAU position has cost: 0.12% of 215000 = 258
+        expected = Decimal("258")
+        assert result == expected
+
+
+class TestGetDefaultStorageCostForUnderlying:
+    """Test get_default_storage_cost_for_underlying function."""
+
+    def test_xau_default(self) -> None:
+        """Test XAU gets 0.12% annual default."""
+        basis, period = get_default_storage_cost_for_underlying("XAU")
+
+        assert basis == Decimal("0.12")
+        assert period == "annual"
+
+    def test_gld_default(self) -> None:
+        """Test GLD gets no storage cost (expense ratio in price)."""
+        basis, period = get_default_storage_cost_for_underlying("GLD")
+
+        assert basis is None
+        assert period is None
+
+    def test_gc_f_default(self) -> None:
+        """Test GC=F gets no storage cost (roll costs deferred)."""
+        basis, period = get_default_storage_cost_for_underlying("GC=F")
+
+        assert basis is None
+        assert period is None
+
+    def test_unknown_underlying_default(self) -> None:
+        """Test unknown underlying gets no storage cost."""
+        basis, period = get_default_storage_cost_for_underlying("UNKNOWN")
+
+        assert basis is None
+        assert period is None
+
+
+class TestPositionStorageCostFields:
+    """Test Position model storage cost fields."""
+
+    def test_position_with_storage_cost_fields(self) -> None:
+        """Test Position can be created with storage cost fields."""
+        pos = Position(
+            id=uuid4(),
+            underlying="XAU",
+            quantity=Decimal("100"),
+            unit="oz",
+            entry_price=Decimal("2150"),
+            entry_date="2025-01-01",
+            storage_cost_basis=Decimal("0.12"),
+            storage_cost_period="annual",
+            storage_cost_currency="USD",
+        )
+
+        assert pos.storage_cost_basis == Decimal("0.12")
+        assert pos.storage_cost_period == "annual"
+        assert pos.storage_cost_currency == "USD"
+
+    def test_position_default_storage_cost_fields(self) -> None:
+        """Test Position defaults for storage cost fields."""
+        pos = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+        )
+
+        assert pos.storage_cost_basis is None
+        assert pos.storage_cost_period is None
+        assert pos.storage_cost_currency == "USD"
+
+    def test_position_serialization_with_storage_costs(self) -> None:
+        """Test Position serialization includes storage cost fields."""
+        pos = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("0.12"),
+            storage_cost_period="annual",
+        )
+
+        data = pos.to_dict()
+
+        assert data["storage_cost_basis"] == "0.12"
+        assert data["storage_cost_period"] == "annual"
+        assert data["storage_cost_currency"] == "USD"
+
+    def test_position_deserialization_with_storage_costs(self) -> None:
+        """Test Position deserialization restores storage cost fields."""
+        pos = create_position(
+            underlying="XAU",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=Decimal("0.12"),
+            storage_cost_period="annual",
+        )
+
+        data = pos.to_dict()
+        restored = Position.from_dict(data)
+
+        assert restored.storage_cost_basis == Decimal("0.12")
+        assert restored.storage_cost_period == "annual"
+        assert restored.storage_cost_currency == "USD"
+
+    def test_position_serialization_with_null_storage_costs(self) -> None:
+        """Test Position serialization handles null storage cost fields."""
+        pos = create_position(
+            underlying="GLD",
+            quantity=Decimal("100"),
+            entry_price=Decimal("2150"),
+            storage_cost_basis=None,
+        )
+
+        data = pos.to_dict()
+
+        assert data["storage_cost_basis"] is None
+        assert data["storage_cost_period"] is None
+        assert data["storage_cost_currency"] == "USD"