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State files updated Oct 31, 2026
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California contractor license

Tanko Bros Inc

Tanko Bros Inc of Sonora holds California license 395633 (C57 Well Drilling). The CSLB file dated Oct 31, 2026 lists it as active.1 It expires Nov 30, 2028.

Active

Tanko Bros Inc, Sonora

License
395633
Class
C57 Well Drilling
Expires
Nov 30, 2028
Bond
$25,000
Workers' comp
Insured to Feb 1, 2027

CSLB file dated Oct 31, 2026

From the CSLB file dated Oct 31, 2026. Not a consumer report; check the board before you hire.

Has the board taken action on this license?

None in the CSLB file dated Oct 31, 2026. Confirm with the board: CSLB license check

What bond, insurance and workers' comp are on file?

Bond
$25,000Ohio Casualty Insurance Company (The), from Jan 1, 2023, continuous
Liability insurance
Not in the CSLB fileCheck with the board
Workers' comp
InsuredState Compensation Insurance Fund, from Feb 1, 2019, to Feb 1, 2027

Who is on this license?

Officer
Marvin K. TankoSince Nov 12, 1980
Responsible managing officer, CEO and president
Dennis P. TankoSince Nov 12, 1980

What work does this license cover?

Issued Nov 12, 1980.

Which other Sonora businesses hold C57 Well Drilling?

What should you check before hiring?

What to ask before you hire

  1. Get the license number in writing. The name on the license should match the name on your contract and invoice.
  2. Check the class covers the job. A license for one trade doesn't cover another. California license classes
  3. Ask for a certificate of insurance sent to you by the insurance agent, not handed over by the contractor. How to read a COI
  4. Ask who will be on site. If a crew works on your property, ask for proof of workers' comp. An exemption on file means the contractor told the CSLB it has no employees.
  5. Put it in a written contract: license number, price, start date and payment schedule. Check the license again on the day you sign.

If the license is lapsed

  1. Don't sign or pay a deposit until the CSLB shows the license active again.
  2. Ask the contractor why. For a bond or insurance lapse, ask for proof that the new bond or policy was filed with the CSLB, then check again.
  3. If work has started, hold further payments, keep the contract, receipts and photos, and file a complaint with Contractors State License Board (CSLB).
  4. Check another contractor. California license lookup

Sources

  1. CSLB License Master (cslb.ca.gov, Oct 31, 2026)
  2. Contractors State License Board (CSLB)