43 CFR §3836.11

1. (a)Beginning in the assessment year that begins after you locate your mining claim, you must expend $100 in labor or improvements for each claim for each assessment year preceding the date on which you file for a small miner waiver.
2. (b)You may perform assessment work on:
   1. (1)Each individual claim;
   2. (2)One or more claims in a group of contiguous lode or placer claims that you own or hold an interest in and that cover the same mineral deposit; or
   3. (3)Adjacent or nearby lands if the work supports development of the minerals on the claim(s).
3. (c)Your total expenditure must equal at least $100 per claim.