I plan to retire at 60 and collect SS widows benefits. I may want to work very part time. I understand the 2020 earnings limit is $18,240/yr which comes to $1,520/mo. If I earn only $12,000 but earn it in 2 or 3 months (vs. $1,000/mo spread over the full year) will I be penalized? In other words is there a "monthly limit" of what I can earn or is there only an annual limit?
No. As long as your earnings for the calendar year of 2020 are below $18,240 you won't lose any of your benefits because of Social Security's earnings test. The monthly breakdown of your earnings is immaterial unless you earn more than calendar year exempt amount.