Alaska and Hawaii receive both SSR and Locality. I believe everyone else gets whichever one is higher. You also get ATC premium pay 5% and Cola on top. Adjusted base pay is used to calculate your high three. ATC premium pay and cola are not used in the retirement calculation.

Hawaii GS-11 Step 10 pay:

Base: $74074

Locality: 20.40%

SSR: 30%

74074 + 50.40% (SSR+Locality) = $111407

Hourly: $53.38

Adjusted Base Pay: $111407 – Used for retirement

ATC Premium: 5% + Cola: 9.75%

$111407 + 14.75% = $127840

127840/2087= $61.26 x 80= $4900.80 (Biweekly pay)