# What are the UK CBAM default values for steel bolts and screws?

Canonical: https://senseible.earth/answers/uk-cbam-steel-bolts-screws-default

HMRC's UK CBAM default for non-stainless bolts without heads is 6.804 tCO2e per tonne below 800 MPa tensile strength and 6.770 at 800 MPa or more. Hexagon socket bolts of non-stainless steel are 5.686, slotted or cross-recessed 5.915, and stainless hexagon bolts 6.597.

## Default values under heading 7318 15

- 7318 15 42: bolts and screws without heads, non-stainless, below 800 MPa: 6.804 tCO2e per tonne.
- 7318 15 48: the same at 800 MPa or more: 6.770.
- 7318 15 58: slotted or cross-recessed heads, non-stainless: 5.915.
- 7318 15 68: hexagon socket head, non-stainless: 5.686.
- 7318 15 75: hexagon head, stainless: 6.597.
- 7318 15 20: bolts for fixing railway track: 3.968.

## Why the code matters

Tensile class, head type and steel grade each change the 8-digit code and the default. Use the code on the UK import declaration, not the shipping bill's Indian HSN, which can differ at 8 digits.

## When actual data pays off

A forger that buys wire rod and heats it by induction may come in well below these defaults, since the UK does not count that power until at least 2029. Only a verified figure can show it, and it must be ready before your buyer files.

## Worked example: 20 tonnes of headless studs

- Studs without heads, 800 MPa or more: code 7318 15 48, default 6.770.
- Embodied emissions on default: 20 x 6.770 = 135.4 tCO2e.
- With an assumed verified actual figure of 2.900: 20 x 2.900 = 58.0 tCO2e.
- Difference on your buyer's return: 77.4 tCO2e.

## What Senseible does here

Senseible reads wire rod purchases, heat treatment fuel and dispatch weights by fastener code, so your own figure can be set against 6.770 or 5.686. We build the figure from your records and check every figure in-house; for the UK it must then be verified by a verifier accredited for UK CBAM. Have your own verifier? Send it to them.

- [Fastener exporters and CBAM](https://senseible.earth/climate-intelligence/cbam-fastener-exporters-india)
- [Map HSN to CN codes](https://senseible.earth/answers/map-indian-hsn-code-to-eu-cn-code)
- [Mixing defaults and actual data](https://senseible.earth/answers/uk-cbam-default-values-mixing-rules)

Sources: [HMRC, UK CBAM iron and steel default values (published 16 October 2026)](https://www.gov.uk/government/publications/check-the-default-values-for-the-carbon-border-adjustment-mechanism-cbam/iron-and-steel-default-values)

Last reviewed 2026-11-02.