Penalty? What indicates there's a penalty of any kind for earning more than $250K? All that does is change your tax bracket, and not the way you may think either. For 2019 tax rates and brackets see https://www.irs.gov/newsroom/irs-provides-tax-inflation-adjustments-for-tax-year-2019

Are you thinking of the AMT?

https://ttlc.intuit.com/community/tax-topics/help/what-is-the-alternative-minimum-tax-amt/00/25614

Or there might be an extra Medicare tax on high earners.

Some investors may owe an additional 3.8% that applies to whichever is smaller: your net investment income or the amount by which your modified adjusted gross income exceeds the amounts listed below.

Here are the income thresholds that might make investors subject to this additional tax:

Single or head of household: $200,000
Married, filing jointly: $250,000
Married, filing separately: $125,000

This 3.8% surcharge Net Investment Income Tax is certainly more significant than the 0.9% Additional Medicare Tax, both apply to thresholds over $250K married filing jointly, and may be what the original poster was asking about.