If you want to know more about the COLA formula, read my July 18, 2019, article: The Calculation: Why The Social Security COLA Will Sink In 2020
In short, the COLA is based on an unusual inflation index – CPI-W – and is determined by averaging the indexes for July, August and September and comparing that number with the same average for the year before. For 2020, the COLA was set at 1.6% with the release of the September inflation report on Oct. 10, 2019: