Repaying Tax Credits After Getting a Job – Story

My story is simple. I was retired at 62, applied for healthcare, received a reduced premium and a waivered amount for coverage due to my income. I decided that social security was not enough income, so I planned to go back to work. I cancelled my coverage when I accepted a job. 30 days later, my healthcare benefits from my job started. There was no overlap in Obamacare coverage and my new coverage. I was shocked when I did my taxes to find out that I was penalized $600.00 for 3 months of coverage for Obamacare – which I NEVER USED! The end result is that 3 months of coverage ended up costing me $1500.00 because I opted to be covered by my job. I feel this was unfair, since I was covered during my period of retirement, but was penalized for getting a job, getting better coverage on my job, AFTER I cancelled my Obamacare coverage!