Not really. You can collect both if you have the 40 required quarters. However, there will be a offset based on your CSR. You will still get something. When I retired under CSR, I asked SS about this since I had only 17 quarters. Had I had the required 40 quarters, I would have gotten less than $100 per month, so I chose not to work to get the remaining quarters. In addition, my husband worked under SS, but because of the pension offset, I was not able to collect under his. CSA pays great benefits, but we get screwed by the SSA.