Calculation below based on $150,000 annual salary -
$150,000 x 60% / $100 x $.77 = $693 Premium/Imputed Income
$693 x 30% estimated tax - $207.90

Annual Earnings        Imputed Income      Estimated Tax (30%)
$150,000                                   $693                     $207.90
$250,000                               $1,155                     $356.50
$500,000                               $2,310                     $693.00
$750,000                               $2,310                     $693.00