Query Parameters

Use URL query parameters on GET requests. Parameter names and enumerated values are case-sensitive. Use the exact lower-case identifiers shown below. Do not send a JSON body, repeat parameter keys or invent selectors.

Common Parameters

Parameter	Type	Rules
`dataset`	String	Required on an initial series/coverage request; one dataset ID from the selected family.
`from`	Period string	Optional inclusive lower observation bound. Monthly `YYYY-MM`; daily `YYYY-MM-DD`.
`to`	Period string	Optional inclusive upper observation bound; must not precede `from`.
`metrics`	Comma-separated metric IDs	Optional unique subset from the dataset. No spaces around IDs. Omit for default metrics.
`release_id`	Opaque string	Optional retained family release; omission selects current. Do not derive it from an observation month.
`page_size`	Whole number	Optional, 1-5,000; default 1,000 observations across the response.
`cursor`	Opaque string	Continuation token on `/series` only. Best sent alone with the same family endpoint.

Blank/whitespace-only from and to are treated as omitted. Literal null, undefined and latest are invalid dates. Omit other optional parameters when unused rather than sending empty strings. Required values must be populated and valid.

Numeric selectors must be whole-number decimal strings: 5 is valid, 5.0, -1, scientific notation and words are not. Date selection and maturity selection are separate.

Market Selectors

Parameter	Values	Where used
`area`	Supported LAD code, syntactically `E` or `W` followed by eight digits.	Every market dataset.
`property_type`	`detached`, `semi_detached`, `terraced`, `flat`.	Every market dataset except price bands.
`property_type=combined`	Combined eligible types.	Only `new_build_deliveries` and `new_build_sales_share`.
`price_band`	`1`, `2`, `3`, `4`, `5`.	`price_bands` only.
`bedroom_group` for flats	`studio_1`, `2`, `3_plus`.	`rental_market`.
`bedroom_group` for houses	`2`, `3`, `4_plus`.	`rental_market`.
`development_size`	`single_home`, `small`, `medium`, `large`.	`development_deliveries`.

flat includes maisonettes. There is no separate bungalow, subtype, studio-only or five-bedroom selector. studio_1 is a combined studio/one-bedroom group, not an exact count of one room or one bed. Rates never accept these market selectors.

price_bands is deliberately combined residential data: sending property_type is an error, not an additional filter. A valid-looking area code must also exist in the selected release.

Rates Selectors

Parameter	Accepted range/options	Meaning
`tenor_months`	Positive whole number, parser limit 1-1,200; node must actually exist.	Select one stored curve maturity. The parser limit is not a promise of a 100-year curve.
`term_years` on `indicative_swap_rates`	1, 2, 3, 5, 7, 10, 15, 20, 25.	Fixed swap-equivalent term.
`term_years` on `forward_starting_swap_rates`	2, 3, 5, 10.	Duration after the selected future start.
`term_years` on `btl_refinancing_scenarios`	2, 5.	Supported fixed-rate product assumption, both at 75% LTV.
`horizon_from_month`	Whole number 0-120, default 0.	Earliest future start/projection point.
`horizon_to_month`	Whole number 0-120, default 120.	Latest future start/projection point, inclusive.
`scenario`	`market_base`, `higher_for_longer`, `rapid_cuts`, `refinancing_stress`.	Scenario selection where the dataset permits it.
`mortgage_product`	One of the 16 documented IDs.	Required for mortgage benchmarks and fixed-product spread datasets.

Horizon bounds must be ordered. They apply only to forward-starting swaps and scenario/path datasets, not spot curves or historical Bank Rate. Equal bounds select one future start.

bank_rate_scenarios, btl_refinancing_scenarios and mortgage_reversion_scenarios default to market_base. financing_stress_scenarios requires an explicit scenario. sonia_forward_path does not accept a scenario override.

Omit a curve node or term selector to return available nodes/terms. The API does not interpolate a customer-requested maturity. A node with no history anywhere in the selected release is rejected; a node that exists historically but not in the requested/latest snapshot can return an empty result.

Parameters Not Accepted

No request in this API accepts a property address, UPRN, floor area, postcode, valuation options, user-defined calculation window, output frequency, currency conversion, SQL, an API key in the query string or a caller-chosen request ID. Use the Data Bank parameters rather than copying a Property Valuation API body.