Send in your paper application with the $200. In the case of E-FIle the tax is paid during the submission process by debit or credit card. Form submitted in E-File will simply be e-mailed to you. One the Form 4 is approved by the ATF the NFA item can be transferred. 

More Information can be found on the ATF's Website:

https://www.atf.gov/rules-and-regulations/national-firearms-act

NFA Ownership Information:

Did you know that owning a suppressor (silencer), machine gun, short barreled rifle or shotgun is legal in the state of Florida? You just need to go through the proper steps on filing the necessary paperwork, at Red Dot Shooting, we handle all the details for you. Here are some basic requirements to purchase & own a NFA item:

You must have a clean record, with no felonies
You must be at least 21 years of age
You must reside in the state of Florida
You must have a valid identification issued by the state of Florida

Class III / NFA weapons such as suppressors, machine guns, short barreled rifles or shotguns & destructive devices carry a $200 tax. AOWs carry a $15 tax. This tax is payable when submitting the Form 4 to the  ATF. The ATF NFA Branch will take anywhere from 6-12 months to process and return a paper Form 4. E-File has been adopted by almost all dealers and has now drastically improved the processing times especially when fingerprints are submitted electronically.

All responsible persons named in the trust or legal entity are required to undergo a background check both by the ATF and again in Florida when the Form 4 has been approved.
All responsible persons must complete the Form 5320.23 with photo attached and provide two FD-258 fingerprint cards in order to initiate the required background check. Fingerprint cards may be ordered from the ATF Distribution Center through the online Distribution Center Order Form, or by calling (703) 870-7525 or (703) 870-7528. Alternatively fingerprints can be scanned as an electronic file and submitted as the Form 4 is processed in E-File.
Chief Law Enforcement Officer (CLEO) certification has been replaced with CLEO notification. The applicant on the Form 1 and the transferee on the Forms 4 and 5 shall forward a completed copy of the application to the chief law enforcement officer of the locality in which the applicant or transferee is located. In addition, all responsible persons must also submit a completed copy of Form 5320.23, to the chief law enforcement officer of the locality in which the responsible person resides.
after July 12, 2016, all applications to make or transfer NFA firearms must be submitted on the new Form 1, Form 4 or Form 5 and a Form 5320.23 must be completed by each responsible person of a trust or legal entity.
After July 12, 2016, CLEO certification is no longer required but applicants must send a copy of the application to make or transfer NFA firearms to their chief law enforcement officer notifying them of the application.
All applications post marked prior to the effective date of July 13, 2016 will be processed according to the current regulations.
All applications post marked on or after the effective date of July 13, 2016 will be processed according to the new regulations set forth by 41F.