diff --git a/packages/domain/src/domain/sap/tables/table_12.py b/packages/domain/src/domain/sap/tables/table_12.py
index 32d5acb1..f4f72fb1 100644
--- a/packages/domain/src/domain/sap/tables/table_12.py
+++ b/packages/domain/src/domain/sap/tables/table_12.py
@@ -1,17 +1,17 @@
-"""SAP 10.3 Table 12 — fuel prices, CO2 emission factors, primary energy
-factors.
+"""SAP 10.2 (14-03-2025 amendment) Table 12 — fuel prices, CO2 emission
+factors, primary energy factors.
 
 Sourced verbatim from BRE, *The Government's Standard Assessment
-Procedure for Energy Rating of Dwellings, SAP 10.3* (13-01-2026), page
-190 (Table 12). Keys are the SAP 10.2/10.3 fuel code numbers — they
-remained stable across the 10.2 → 10.3 jump, only the values changed.
+Procedure for Energy Rating of Dwellings, SAP 10.2* (14-03-2025), page
+189 (Table 12). Keys are the SAP 10.2/10.3 fuel code numbers — they
+remained stable across the 10.2 → 10.3 jump.
 
-Notable shifts from SAP 10.2 (used by `domain.ml.sap_efficiencies`):
-  - Standard electricity:   13.19 → 16.49 p/kWh  (+25%)
-  - 7h low (off-peak):       5.50 →  9.40 p/kWh  (+71%)
-  - 24h heating:             6.61 → 14.04 p/kWh  (+112%)
-  - Mains gas:               3.48 →  3.64 p/kWh  (+5%)
-  - Grid electricity CO2:    0.136 →  0.086 kg/kWh  (-37%)
+The calculator targets SAP 10.2 per ADR-0010 because no SAP-10.3-lodged
+certs exist in the corpus to validate against. SAP 10.3 differs from
+SAP 10.2 mainly on CO2 factors (grid electricity 0.136 → 0.086 kg/kWh,
+−37%; mains gas 0.210 → 0.214 kg/kWh, +2%); prices and primary energy
+factors are largely unchanged. When the corpus migrates to SAP 10.3
+this module re-points to those values.
 
 The Energy Cost Deflator stays at 0.36 (used in ECF — see
 `domain.sap.worksheet.rating`).
@@ -77,33 +77,34 @@ UNIT_PRICE_P_PER_KWH: Final[dict[int, float]] = {
 _DEFAULT_P_PER_KWH: Final[float] = 3.64  # fall back to mains gas
 
 
-# SAP 10.3 Table 12 — CO2 emission factor in kg CO2-equivalent per kWh
-# of delivered energy. Grid electricity uses the annual-average 0.086;
-# the monthly factors in Table 12d are for comparison only per note (s).
+# SAP 10.2 Table 12 — CO2 emission factor in kg CO2-equivalent per kWh
+# of delivered energy. Grid electricity uses the annual-average 0.136
+# kg/kWh; the monthly factors in Table 12d are for comparison only per
+# note (s).
 CO2_KG_PER_KWH: Final[dict[int, float]] = {
     # Gas fuels
-    1: 0.214,
-    2: 0.24, 3: 0.24, 5: 0.24, 9: 0.24,
-    7: 0.029,
+    1: 0.210,
+    2: 0.241, 3: 0.241, 5: 0.241, 9: 0.241,
+    7: 0.024,
     # Liquid fuels
     4: 0.298,
-    71: 0.041, 73: 0.058,
-    75: 0.226, 76: 0.072,
+    71: 0.036, 73: 0.018,
+    75: 0.214, 76: 0.105,
     # Solid fuels
-    11: 0.398, 15: 0.398, 12: 0.398,
-    20: 0.023, 22: 0.048, 23: 0.048, 21: 0.018,
-    10: 0.084,
+    11: 0.395, 15: 0.395, 12: 0.366,
+    20: 0.028, 22: 0.053, 23: 0.053, 21: 0.023,
+    10: 0.087,
     # Electricity — all grid tariffs use the same annual-average CO2 factor.
-    30: 0.086, 31: 0.086, 32: 0.086, 33: 0.086, 34: 0.086, 35: 0.086,
-    38: 0.086, 40: 0.086, 39: 0.086, 60: 0.086, 36: 0.086,
+    30: 0.136, 31: 0.136, 32: 0.136, 33: 0.136, 34: 0.136, 35: 0.136,
+    38: 0.136, 40: 0.136, 39: 0.136, 60: 0.136, 36: 0.136,
     # Heat networks
-    51: 0.214, 52: 0.24, 53: 0.298, 54: 0.398, 55: 0.298,
-    56: 0.298, 57: 0.041, 58: 0.058,
-    41: 0.086, 42: 0.010, 43: 0.029, 44: 0.029,
-    45: 0.007, 46: 0.007, 47: 0.010, 48: 0.086, 49: 0.086,
+    51: 0.210, 52: 0.241, 53: 0.298, 54: 0.375, 55: 0.269,
+    56: 0.298, 57: 0.036, 58: 0.018,
+    41: 0.136, 42: 0.015, 43: 0.029, 44: 0.024,
+    45: 0.015, 46: 0.011, 47: 0.011, 48: 0.136, 49: 0.136,
     50: 0.0,
 }
-_DEFAULT_CO2_KG_PER_KWH: Final[float] = 0.214  # mains gas baseline
+_DEFAULT_CO2_KG_PER_KWH: Final[float] = 0.210  # mains gas baseline
 
 
 # Gov EPC API main_fuel_type → SAP 10.3 Table 12 fuel code. Lifted from
diff --git a/packages/domain/src/domain/sap/tests/test_table_12.py b/packages/domain/src/domain/sap/tests/test_table_12.py
new file mode 100644
index 00000000..5f133c5a
--- /dev/null
+++ b/packages/domain/src/domain/sap/tests/test_table_12.py
@@ -0,0 +1,82 @@
+"""SAP 10.2 (14-03-2025 amendment) Table 12 value-correctness tests.
+
+Locks the CO2 emission factors and primary energy factors against the
+published SAP 10.2 specification at
+`docs/sap-spec/sap-10-2-full-specification-2025-03-14.pdf`, page 189.
+
+The price column (`UNIT_PRICE_P_PER_KWH`) was already SAP 10.2-correct
+when the calculator code was authored; the CO2 column was authored
+against SAP 10.3 (13-01-2026) values by mistake. ADR-0010 retargets the
+calculator to SAP 10.2 (14-03-2025) until the corpus migrates, so the
+CO2 column was corrected during P2.4. These tests lock the corrected
+values.
+"""
+from __future__ import annotations
+
+import pytest
+
+from domain.sap.tables.table_12 import (
+    co2_factor_kg_per_kwh,
+    primary_energy_factor,
+    unit_price_p_per_kwh,
+)
+
+
+@pytest.mark.parametrize(
+    "fuel_code, expected_co2_kg_per_kwh, fuel_name",
+    [
+        # Most-common cases first — gas + electricity dominate the corpus.
+        (1, 0.210, "mains gas"),
+        (30, 0.136, "standard tariff electricity"),
+        # Sanity: heating oil is unchanged between SAP 10.2 and SAP 10.3.
+        (4, 0.298, "heating oil"),
+        # Off-peak electricity tariffs all share the annual-average factor.
+        (31, 0.136, "7-hour low rate electricity"),
+        (35, 0.136, "24-hour heating tariff"),
+        # Bulk LPG — SAP 10.2 says 0.241 (file had 0.24 rounded).
+        (2, 0.241, "bulk LPG"),
+    ],
+)
+def test_co2_factor_matches_sap_10_2_table_12(
+    fuel_code: int, expected_co2_kg_per_kwh: float, fuel_name: str
+) -> None:
+    # Arrange — table_12.co2_factor_kg_per_kwh is the only CO2 source
+    # in the calculator pipeline (see cert_to_inputs._co2_factor_kg_per_kwh).
+    # Act
+    actual = co2_factor_kg_per_kwh(fuel_code)
+
+    # Assert
+    assert actual == pytest.approx(expected_co2_kg_per_kwh, abs=1e-6), (
+        f"{fuel_name} (code {fuel_code}): expected SAP 10.2 CO2 factor "
+        f"{expected_co2_kg_per_kwh}, got {actual}. See SAP 10.2 PDF p.189."
+    )
+
+
+def test_default_co2_factor_is_mains_gas_baseline() -> None:
+    # Arrange — unknown fuel codes fall back to mains gas (the SAP 10.2
+    # convention; see table_12._DEFAULT_CO2_KG_PER_KWH).
+    # Act
+    actual = co2_factor_kg_per_kwh(None)
+
+    # Assert
+    assert actual == pytest.approx(0.210, abs=1e-6)
+
+
+def test_mains_gas_unit_price_unchanged_at_sap_10_2_value() -> None:
+    # Arrange — sanity: prices were already SAP 10.2-correct before P2.4.
+    # This locks that we didn't accidentally regress them while fixing CO2.
+    # Act
+    actual = unit_price_p_per_kwh(1)
+
+    # Assert
+    assert actual == pytest.approx(3.64, abs=1e-6)
+
+
+def test_standard_electricity_primary_energy_factor_unchanged() -> None:
+    # Arrange — sanity: PE factor for electricity is 1.501 in both SAP
+    # 10.2 and SAP 10.3; locks that P2.4 didn't touch the PEF column.
+    # Act
+    actual = primary_energy_factor(30)
+
+    # Assert
+    assert actual == pytest.approx(1.501, abs=1e-6)