SOT : Special Occupational Tax Payer or TAX STAMPER is an individual who owns registered machineguns.
You pay a one-time $ 200 transfer tax for each serial numbered part
Must live in a state where legal. Form must be signed by a Sheriff/Chief of police to purchase unless registered to a Corporation or LLC..a way around LE signature. Submit to ATF after paying for the machinegun, wait about 3 months for approval.
Machineguns MUST be pre-may 1986 Mfg to be transferrable. New SBR/SBS or silencers no problem.
For a machine gun only.... you do NOT have to pay any tax if it is a SBR. If you intend to move the sear from that machine gun and use it in another.... you would need to have the original machine gun registered as a SBR before you could leave it sear-less.
This is the case with HK models that have trigger packs that can be moved from one gun to another.
First off you need to apply for your FFL then you can proceed to obtain your SOT class 3 license. Remember before you go in for all the paperwork make sure you are zoned if you plan on doing this out of your house the FFL is good for 3yrs and the SOT is due every year July1 $500. IF you are just planning to do this for personal gain to get machine guns dont bother you have to make sales otherwise it is tax evasion it just makes sense.
If you are doing this as a consumer the other option for sign off is doing a living trust besides the LLC route. I have many customers go this route it is not a business and therefore not as complicated.