* Social Security (United States): You can create an online account at the Social Security Administration (SSA) website (ssa.gov). Your account will show your earnings history and the number of credits you've earned. You can also contact the SSA directly by phone or mail.
* Other government pension plans (e.g., federal, state, local): Each government agency will have its own system for tracking and reporting retirement credits. Check your agency's website or contact your human resources or pension administrator. They will provide information about your account balance and the number of years of service credited.
* Private sector 401(k), 403(b), pension plans, etc.: Your statements from your retirement plan provider will show your account balance, contributions, and investment performance. While these statements don't usually use the term "work credits," they show the contributions made and the impact of those contributions on your future retirement benefits. The number of *years* of contributions will be a reflection of how many "credits" you have toward vesting and retirement (vesting is the point where the employer's contributions become yours). Contact your plan administrator if you have questions.
* Other countries: Retirement systems vary significantly by country. Consult your country's social security administration or equivalent agency for information on your retirement credits or equivalent.
In short, you need to identify the specific retirement system(s) you're participating in and then consult that system's resources to see your accumulated credits or equivalent information.