Reference Rates

These datasets expose published observations, not valuations or forward scenarios. Use daily date filters and read the actual returned observation dates.

Bank Rate

Dataset: bank_rate. Required: dataset only. Metric: rate_pct, unit percent, basis observed.

GET /v1/rates/series?dataset=bank_rate
GET /v1/rates/series?dataset=bank_rate&from=2026-08-01&to=2026-09-14

The Bank of England policy-rate reference. An unchanged value on consecutive stored dates is not a data error. The API returns retained observations; it does not promise a row for every calendar day or manufacture weekend observations.

Do not interpret this series as a retail mortgage rate, overnight transaction rate or forecast of the next policy decision. Use bank_rate_scenarios for explicitly modelled future assumptions.

SONIA Overnight Rate

Dataset: sonia_overnight. Required: dataset only. Metric: rate_pct, unit percent, basis observed.

GET /v1/rates/series?dataset=sonia_overnight&from=2026-09-01&to=2026-09-14

The observed sterling overnight benchmark for the returned date. It is not a forward-looking term SONIA rate, a multi-day realised compounded rate or a borrower's all-in financing cost.

The latest available observation may precede the request date. Bank Rate and SONIA measure different things and need not be identical. Their difference is not an error in either series.

SONIA Compounded Index

Dataset: sonia_compounded_index. Required: dataset only. Metric: index_value, unit index, basis observed.

GET /v1/rates/series?dataset=sonia_compounded_index&from=2026-09-01&to=2026-09-14

An official index of compounded overnight SONIA. Its level is an index number, not a percentage yield. Do not display a percent sign or subtract it from Bank Rate as though the units match.

This endpoint does not calculate accrued loan interest or a realised compounded rate over arbitrary dates. Those calculations require their own contract, calendar and day-count treatment. The API does not infer them from a from/to filter.

Shared Options and Coverage

All three accept from, to, metrics, release_id and page_size, with cursor continuation. None accepts a tenor, term, horizon, scenario, mortgage product, area or property type.

Omit dates for the latest retained observation. Supply both equal dates for an exact day. A day with no retained observation returns an empty selection rather than the previous working day's value. Historical observations can revise in later releases; retain the release identity when comparing results.