I might have to step back from my statement. It applies to formal relocation. If you informally move from San Francisco to San Jose, there would be no compensation adjustment. Similarly, if you informally moved from San Francisco to Winston-Salem, N.C. there should be no compensation adjustment. If your work from home agreement has no in-office requirement then there should be not problem, but I would expect a work from home agreement with no in-office requirement to have a base salary compatible with some average cost of living base.