Do I pay social security on my pension

No.  Pension payments, annuities, and the interest or dividends from your savings and investments are not earnings for Social Security purposes. You may need to pay income tax, but you do not pay Social Security taxes.

But if you get SSA-1099 Social Security benefits some of it may be taxable based on your total income.

Up to 85% of Social Security becomes taxable when all your other income plus 1/2 your social security, reaches:

Married Filing Jointly: $32,000

Single or head of household: $25,000

Married Filing Separately: 0