About Enphase Energy equity
Enphase Energy (ENPH, HQ CA) grants RSUs to employees and also runs an Employee Stock Purchase Plan with a quarterly vesting cadence.
Federal withholding at vest
Enphase Energy applies the standard federal supplemental withholding: 22% flat on RSU ordinary income, rising to 37% once year-to-date supplemental wages exceed $1M. Both rates are below the top bracket, which means high earners typically owe additional federal tax at filing.
State withholding
Because Enphase Energy is headquartered in CA, your state withholding defaults to that state unless your work location is recorded differently. If you moved during the grant-to-vest window, the state that taxes each tranche is determined by workday allocation, not by your HQ.
Quarterly estimates
Tech earners with meaningful Enphase Energy RSU income often need quarterly estimated payments in addition to payroll withholding. The safe-harbor rule (110% of prior-year tax, for AGI over $150k) usually determines the minimum you need to send per quarter to avoid an underpayment penalty.
What to do next
- Run the RSU vesting calculator against your next tranche.
- Read the complete RSU guide.
- Match with a fiduciary advisor before a meaningful event.