What on god's green earth are you talking about?

it depends. Medicare Part B is usually deducted from you social security, and its premiums are calculated using your modified adjusted gross income from two years prior to determine if you pay the standard premium or a higher income adjustment amount.

In other words it depends on their Medicare Part B coverage, and whether they have a Supplemental or Medigap Plan, or an Advantage Plan.

There are a lot more details I am leaving out, but in general, unless they have a Medicare Advantage Plan, the Medicare Part B premiums are usually deducted from your social security check, and that should remain constant for the entire year unless they had a significant increase in income the prior two years, such as through an inheritance, sale of a principle residence, etc. In that case the premiums for Part B will be higher, and thus their social security check they receive each month will be less.

It can also be affected if they have social security take out extra federal income tax from their social security monthly benefit.