I am nearing retirement and have read in 2 different resources that the limits of modified taxable income for married ccouples is $150,000 and single is $100,000. I also read in other resources very emphatically that the limits of the MTI is $100,000 for both married and single. Which is right?

There is one Modified AGI limit for Roth contributions and a separate one for Roth conversions.

To make a contribution to a Roth, there must be earned income and modified AGI for a married couple must be $150,000 or less. A partial contribution is allowed when modified AGI is between $150,000 and $160,000.

To convert a traditional IRA to a Roth, Modified AGI must be $100,000 or less for a married couple or a single person.