How does the IRS know what portions of my estimated payment goes to federal tax, SS, and medicare?

[ThisIsSoTaxing]

I am yet to make my first self employment quarterly tax payment.  I've read a lot of web sites looking for advise on how to go about making the payment.  My expectation was that there was some form I would need to submit that breaks it all out so the government knows where to direct each portion of the payment (e.g. this much for federal tax, that much for social security, and that much for medicare).  But as far as I can tell, there is no such form.  I just go to EFTPS and pay the total amount.  And I will keep my own records so that I can report it properly on my annual taxes.  Does that sound right?

[Bsch4477]

If you're self-employed, you pay the combined employee and employer amount. This amount is a 12.4% Social Security tax on up to $160,200 of your net earnings to and a 2.9% Medicare tax on your entire net earnings.

You don’t have concern yourself with that. You just have to make payments that cover both income tax and self employment tax which are calculated separately by TurboTax. 

[VolvoGirl]

Yes that's right.  The Estimated payments go towards it all.  Your final tax due includes both the regular income tax and the self employment tax (for SS & Medicare).  So you don't have to break it out.  

[MaryK4 · Accepted solution]

Yes, when you make your estimated taxes on EPTPS, you must make sure you indicate what period to apply the estimated taxes to, but there is no breakdown for self-employed because the FICA and income tax is calculated and reported on the 1040.