Assessment Work
Annual labor or improvements worth at least $100 per claim, required to maintain an unpatented mining claim as an alternative to maintenance fees.
Detailed Definition
Assessment work refers to the annual labor or improvements that must be performed on an unpatented mining claim to maintain its validity. This is an alternative to paying annual maintenance fees.
Requirements: - Minimum $100 worth of labor or improvements per claim per year - Must tend to develop or benefit the claim - Assessment year runs from September 1 to September 1 - Affidavit of assessment work must be filed with BLM
Qualifying activities: - Underground development work - Surface excavation and sampling - Road construction for mine access - Geological and geophysical surveys - Core drilling and assaying
Documentation requirements: - Detailed description of work performed - Dates and location of work - Value of labor and materials - Filed with BLM by December 30 following assessment year
Small Miner Waiver: Claimants holding 10 or fewer claims may file for a waiver of maintenance fees if assessment work is performed and properly documented.
Related Terms
BLM
The Bureau of Land Management, the federal agency that administers public lands including mining claim filings and maintenance.
Unpatented Claim
A mining claim that has not been converted to private ownership; the federal government retains title to the land.
Maintenance Fee
The annual fee paid to the BLM to maintain an unpatented mining claim, currently $200 per claim (2025).