Fiscal partition: domestic_rates note gives only the council tax placement of NI domestic rates #2662

Problem

policyengine_uk/data/fiscal_partition.yaml maps the domestic_rates head to the Table A.5 "Council tax" row, and its obr_line_note says only that "The OBR adds Northern Irish domestic rates to its council tax receipts".

domestic_rates is the whole Northern Ireland domestic bill: the regional rate plus the council's district rate, levied as one bill (Rates (Northern Ireland) Order 1977, art 9(1)). Land & Property Services reports £889.5m of domestic rates paid in 2024-25.

The OBR's March 2026 detailed forecast tables show NI domestic rates in two places, and label neither as regional or district:

• Expenditure Table 4.1 (council tax receipts, a breakdown of Table A.5's council tax line), row 16 "NI domestic rates": £0.494bn in every column from the 2024-25 outturn to 2030-31.
• Receipts Table 3.2 (other taxes, consistent with Table A.5's "Other taxes" line), row 6 "Northern Ireland domestic rates": £0.485bn in 2024-25.

ONS records the regional domestic rate as a central government tax (£498m in 2024-25) and district domestic rates with council tax, as a local government tax (£441m). The model's own reading, in the gov.economic_assumptions.yoy_growth.finance_ni.domestic_rates comment, is that Table 4.1 appears to be the district rates and Table 3.2 the regional rate. The partition note predates that analysis and describes only the council tax placement.

Fix

Rewrite the note to give both places, with the coverage stated as inference ("appears to"), since the OBR defines neither line. Record on the Other taxes row of uncovered_receipts that it is partly measured. The obr_line and obr_table_3_1 values are reviewed in the PR.

Found in the NI business rates reconciliation (#2343, #2344). Related: PolicyEngine/policyengine-uk-data#520 (the dataset's obr/domestic_rates calibration target reads the Table 4.1 line alone).