I did not make any proactive payments to social security, can I still make a payment to social security?

[mathmike100]

I am self employed Realtor.

[Critter-3]

SE taxes (SS & Medicare) are computed from the profits of your SE income on the tax return and are paid using that process ... you cannot pay them any other wat.  

[Opus 17]

If you are self-employed, you are generally required to make estimated tax payments to the IRS to cover your expected income tax plus self-employment tax.  These estimated payments are due 4 times a year (generally April 15, June 15, Sept 15 and January 15).  Your tax return calculates your actual taxes owed.  If you made more estimated payments than you owe, you get a refund, and if you owe more than you paid, you must pay the difference when you file your return.  If you don't make estimated payments during the year, you can be charged an under-payment penalty even if you pay in full when you file your return.  

It is too late to make estimated payments for the 2020 tax season, just file your return and pay what you owe.  Your first estimated payment for the 2021 season is due May 17 (the deadline was extended).

However, the exact amount of that payment that is credited to you social security account depends entirely on your taxable income earned from working, and you can't decide to pay more to build up a retirement fund. 

[VolvoGirl]

On your Tax Return.........Self Employment tax (Scheduled SE) is automatically generated if a person has $400 or more of net profit from self-employment. You pay 15.3% SE tax on 92.35% of your Net Profit (If it is greater than $400). The 15.3% self employed SE Tax is to pay both the employer part and employee part of Social Security and Medicare (FICA). So you get social security credit for it when you retire.

You must be asking about the quarterly estimated payments to cover the SE tax?  That is like withholding if you were an employee.  You don't pay it directly to Social Security.