Had a conversation with a local Maine rep who was willing to look up my account and answer my questions. This morning's "helpful phone person" was in the Jamaica, NY office.
First payment is due August the latest. Amount is higher than in the letter due to a .036% raise and last year's income.
Payments are made on a fair income estimate. Adjustments will be made in January if I am under (or overpaid).
Adjustments will continue to be made if I continue to work and raise my average wages.
Breathing again.
Mary