How to Read a Washington Contractor License Number

Short Answer: A Washington contractor registration number is usually a mix of letters taken from the business name and digits. It is different from the UBI number, and a change in business structure usually means a new registration number.

Quick Facts

Washington contractor registration numbers look cryptic at first: something like a cluster of capital letters followed by digits and sometimes more letters. Once you know the pattern, they are easy to read, and reading them carefully helps you spot a number that does not belong to the business in front of you.

The Typical Format

Most construction contractor registration numbers issued by L&I combine:

• letters derived from the business name, often the first several letters,
• digits, and
• sometimes trailing letters or digits.

For example, a business named “Bridgewater Electric” might hold a number that begins with letters resembling “BRIDGE”. The exact construction varies, especially for older registrations and for electrical and plumbing records, so treat the pattern as a helpful hint, not a rule. The only reliable test is to look the number up.

Why the Letters Help You

Because the leading letters usually echo the business name, a mismatch is a quick warning sign. If “Evergreen Roofing” hands you a number starting with completely unrelated letters, ask why. There may be a good reason, such as a renamed business, but you should hear it.

The License Number vs the UBI

Washington businesses also have a UBI (Unified Business Identifier), a nine-digit number used across state agencies for business licensing and taxes.

Our profiles show both when the state file includes the UBI.

Where to Find the Number

• On the Notice to Customer, which RCW 18.27.114 requires on most residential jobs of $1,000 or more.
• On bids, contracts and invoices.
• In advertising; Washington law treats advertising with a false or expired registration number as a violation.
• On L&I Verify and in our Washington Contractor License Lookup, by name search.

Why a Business Can Have Several Numbers

A registration belongs to a specific business structure. When a sole proprietor forms an LLC, or partners incorporate, the new entity registers separately and receives a new number. The old record stays in the file, usually marked EXPIRED or RE-LICENSED. Status meanings are covered in Washington Contractor License Statuses Explained.

This matters because:

• your contract should name the entity that holds the current ACTIVE registration,
• the bond and insurance on file belong to that registration,
• a claim against an old, expired registration may not reach the current bond.

Watch out: Someone quoting an old number from a business they used to run is not registered under that number now. Always check the status attached to the exact number you were given.

Electrical and Plumbing Numbers

Electrical contractor licenses and individual electrician and plumber certificates have their own numbering. Check the business number and, separately, the individual worker’s certificate number on L&I Verify.

How to Verify a Number in Four Steps

1. Get the number in writing.
2. Search it in our lookup or on L&I Verify.
3. Confirm the business name on the record matches the contract.
4. Confirm the status is ACTIVE and the bond and insurance are current.

Common Mix-Ups

• Typing O for 0 or I for 1. If a search fails, try swapping similar characters.
• Searching a trade name. The record is under the legal name; search distinctive words.
• Using the UBI in the registration field. They are different numbers.
• Copying a number from an old truck decal. Ask for the current number.

What a Number Cannot Tell You

A valid number proves registration, not quality. Pair it with references, a detailed contract and the Questions to Ask Before Hiring a Contractor.

A Worked Example: Matching a Number to a Contract

You receive a bid from “Cascade Ridge Builders LLC” with a registration number printed in the footer. Here is a quick way to read it.

1. Look at the leading letters. Do they plausibly echo “Cascade” or “Cascade Ridge”? If they look entirely unrelated, make a note to ask.
2. Search the exact number. The record should show a legal name. Compare it with the name on the bid, including “LLC” or “Inc”.
3. Read the status and dates. ACTIVE, with an expiry date after your planned project end, is what you want to see.
4. Read the bond and insurance lines. Both should be current.
5. Search the name as well. If you find an older record for “Cascade Ridge Builders” as a sole proprietorship, that is normal history, as long as the number on your bid is the current ACTIVE one.

If any step does not line up, ask the contractor for an explanation in writing before you sign. Honest businesses can usually explain a renamed entity or a recent re-registration in a sentence.

Numbers in Advertising

Washington’s registration law expects contractors to use their registration number when they advertise. When you see an ad, a yard sign or a vehicle with a number on it, you can check it in seconds. Ads with no number, or a number that resolves to a different business, deserve extra caution.

Keeping a Record

Write the registration number on the first page of your contract and in your project notes, along with the date you checked it. If you later need to make a claim, the number is how L&I, the surety and the courts identify the business.

Electrical and Plumbing Workers on Site

For electrical and plumbing work, the people doing the work also hold individual certificates. You can ask to see a worker’s certificate card and look up the certificate on L&I Verify, separately from the business number. It is a reasonable question, and a professional will not mind.

Bottom Line

Read the letters for a quick sanity check, then verify the number. The record attached to it is what tells you whether the bond and insurance behind your project are real and current.