---
title: "Zero-coupon government yield curve (NSS)"
method: GET
path: "/api/v1/norges-bank/zero-coupon-yields"
tags: ["Central Banks & Monetary"]
---

# Zero-coupon government yield curve (NSS)

`GET /api/v1/norges-bank/zero-coupon-yields`

Nelson-Siegel-Svensson parameterised zero-coupon yield curve for Norwegian government securities. Daily series per benchmark tenor. Source: GOVT_ZEROCOUPON dataflow.

## Query parameters

- `last_n` integer — Return last N observations per tenor.

## Response `200`

Zero-coupon yield observations per tenor.

- EnvelopeListNorgesBankZeroCouponDatum
  - `data` NorgesBankZeroCouponDatum[], required
    - `DECIMALS` string, nullable — Number of decimal places reported by the source.
    - `COLLECTION` string, nullable — SDMX collection indicator (e.g. end-of-period, average).
    - `UNIT_MULT` string, nullable — SDMX unit multiplier code (0 = units, 3 = thousands, 6 = millions).
    - `CALCULATED` string, nullable — Flag indicating whether the value is calculated or directly observed.
    - `CALC_METHOD` string, nullable — Calculation method code for observation-level attributes.
    - `FREQ` string, required — Frequency code.
    - `FREQ_name` string, required — Frequency label.
    - `TENOR` string, required — Tenor code (1Y, 3Y, 5Y, 10Y, etc.).
    - `TENOR_name` string, required — Tenor label.
    - `TIME_PERIOD` string, required — Observation date.
    - `value` union — Nelson-Siegel-Svensson zero-coupon yield (percent).
      - number
      - integer
      - string
  - `meta` SugraMeta, required — Metadata attached to every /api/v1/* response envelope.
    - `endpoint` string, required — Requested endpoint path.
    - `data_time` string, required — ISO 8601 UTC timestamp of the source data, not of the request.
    - `response_time` string, required — ISO 8601 UTC timestamp when this response was produced.
    - `provider` string, required — API name and version.
    - `source` string, nullable — Identifier of the primary upstream source used for this response.
    - `attribution` string, nullable — Human-readable attribution mandated by an upstream source (e.g. a securities regulator or self-regulatory organization). Present only on responses whose source requires the owner and source to be clearly identified. Do not remove or alter it when using the response.
    - `fallback_used` boolean, nullable — True when the primary source failed and a fallback produced the data.
    - `fallback_chain` string[], nullable — Ordered list of sources attempted, in the order they were tried.
    - `cached` boolean, nullable — True when this response was served from the internal cache.
    - `stale` boolean, nullable — True when the cached response was returned after the upstream rate-limited or errored. Clients can use this to detect degraded data.

## Other responses

- `401` — Missing or invalid `x-api-key` header. JSON body with a stable `code` distinguishing `missing_api_key` (no header sent) from `invalid_api_key` (header sent, key not accepted); any other 401 source carries the generic `unauthorized` with its detail as `reason`. Plus `hint`. `plan` is always null on 401 - an unauthenticated request has no plan; quota exhaustion is 429, not 401.
- `422` — Validation Error
- `429` — Daily rate limit exceeded. Check `X-RateLimit-Reset` for the next window.
- `503` — Upstream source is temporarily unavailable. Retry after a short delay.

---

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