Ask Social Security Questions and Get Answers ASAP
Did you receive a W-2 or 1099 from union business? You actually get credit for any Social Security wages as long as they were reported on a payroll tax return and a W-2 was generated. It does not matter whether any withholding was actually remitted to the IRS. It is the IRS's job to collect any withholding that has not been paid over to them.
If they did not give you a W-2 but instead a 1099, you would have needed to file Schedule C and SE which are attached to your 1040 form. Schedule SE is for self-employment income where you have to pay both the employee and employer portion of the FICA tax.
Let me know what type of tax statement you received documenting your earnings and withholding for those year. I hope that can answers your question. Let me know if I can clarify anything or answer any additional questions. Jonathan