If I worked in social security employment for 23 years then work in Railroad employment for the last 22 years and retire at age 65, full retirement age 67, and I begin drawing my railroad at age 65 with 22 years of railroad employment can I earn delayed retirement credits for social security up until age 70 and at that time have social security certify those credits to the RR board and get an Increase in benefit from the RR board?
Even if you're drawing Railroad Retirement (RR) benefits, you can still accrue delayed retirement credits (DRC) on your Social Security (SS) retirement benefit rate from your full retirement age (FRA) until age 70. However, that wouldn't necessarily guarantee that you would receive a higher combined amount when you reach age 70.
RR pensions are based on a combination of 2 tiers. Tier 1 benefits are basically a substitute for SS benefits, whereas tier 2 benefits are based solely on RR work and are essentially a company pension. If and when you apply for both RR and SS benefits, you will receive the higher of a) your SS rate or b) your tier 1 RR rate, plus c) any tier 2 RR benefits for which you qualify. Thus, you would likely only benefit from any DRCs that you earn from Social Security if your age 70 SS rate ends up being higher than your tier 1 RR rate.