What's the NAICS and SIC code for an engineering consulting firm?
For an engineering consulting firm, use NAICS 541330 (Engineering Services) in the US and SIC 71129 (Other engineering activities) in the UK.
United States, NAICS 2022
541330 Engineering Services
Engineering Services, including engineering consulting.
SBA small business limit: $25.5 million average annual receipts.
United Kingdom, SIC 2007
71129 Other engineering activities
Other engineering activities, including engineering consultancy.
Use this code when you register with Companies House or file your confirmation statement.
When a different code fits better
These are the codes most often confused with the main answer. Pick by the activity that earns most of your revenue.
| Code | Title | Use it if |
|---|---|---|
| NAICS 541380 | Testing Laboratories and Services | you mainly run testing laboratories |
| NAICS 541690 | Other Scientific and Technical Consulting Services | you mainly give scientific or technical advice outside engineering |
| SIC 71121 | Engineering design activities for industrial process and production | you design industrial processes |
| SIC 71122 | Engineering related scientific and technical consulting activities | you mainly give engineering-related scientific or technical advice |
Good to know
Engineering is one of the SBA codes with special exceptions; check the size standards on the code page.
You can list more than one code. Companies House accepts up to four SIC codes, and SAM.gov lets you add several NAICS codes, with one marked as primary.
What the code affects
- SBA programs and federal contracts: your NAICS code sets the size limit you must stay under to count as small. Check your size.
- SAM.gov registration: contracting officers search by NAICS, so list every code you can deliver work under.
- Companies House: your SIC code appears on the public register and in your confirmation statement.
Related business types
Codes checked against the US Census 2022 NAICS index and the ONS UK SIC 2007 index. Information only; confirm with the agency you file with.