Aha! I figured out why we have different numbers.
SSA publishes a booklet that explains all about it. Of course, it's more complicated than you or I thought! It's
much easier to read (in a nice little chart) in the booklet, which is
https://www.ssa.gov/pubs/EN-05-10536.pdf
Essentially, as you make more (Modified Adjusted Gross Income), you pay more, after $85,000. As you make a lot more, you pay a LOT more.
The standard Part B premium for 2019 is $135.50. If you’re single and filed an individual tax return, or married and filed a joint tax return, the following chart applies to you:
Modified Adjusted Gross Income (MAGI)
Part B monthly premium amount
Prescription drug coverage monthly premium amount
Individuals with a MAGI of $85,000 or less
Married couples with a MAGI of $170,000 or less
2019 standard premium= $135.50
Your plan premium
Individuals with a MAGI above $85,000 up to $107,000
Married couples with a MAGI above $170,000 up to $214,000
Standard premium + $54.10
Your plan premium + $12.40
Individuals with a MAGI above $107,000 up to $133,500
Married couples with a MAGI above $214,000 up to $267,000
Standard premium + $135.40
Your plan premium + $31.90
Individuals with a MAGI above $133,500 up to $160,000
Married couples with a MAGI above $267,000 up to $320,000
Standard premium + $216.70
Your plan premium + $51.40
Modified Adjusted Gross Income (MAGI)
Part B monthly premium amount
Prescription drug coverage monthly premium amount
Individuals with a MAGI above $160,000 up to $500,000
Married couples with a MAGI above $320,000 up to $750,000
Standard premium + $297.90
Your plan premium + $70.90
Individuals with a MAGI equal to or above $500,000
Married couples with a MAGI equal to or above $750,000
Standard premium + $325.00
Your plan premium + $77.40
If you’re married and lived with your spouse at some time during the taxable year, but filed a separate tax return, the following chart applies to you:
Modified Adjusted Gross Income (MAGI)
Part B monthly premium amount
Prescription drug coverage monthly premium amount
Individuals with a MAGI of $85,000 or less
2019 standard premium= $135.50
Your plan premium
Individuals with a MAGI above $85,000 up to $415,000
Standard premium + $297.90
Your plan premium + $70.90
Individuals with a MAGI equal to or above $415,000
Standard premium + $325.00
Your plan premium + $77.40
Maybe I shouldn't have copied all that. It's impossible to make sense of without looking at the chart. </end dumb Medicare premiums>