The form you need to complete is VAF4A when applying from abroad. For information, if you want to look at the form used from within the UK FLR(M) (not applicable to you if applying from the USA), it has a quite a bit of info. Links to FLR(M) and the guide below :
https://www.gov.uk/government/uploads/s ... _11-14.pdf
https://www.gov.uk/government/uploads/s ... _11-14.pdf
You will be applying for a spouse (also known as a settlement) visa. It should be granted initially for a period of 30 months.
The visa will need to be renewed after 2.5 years, meeting all the same requirements again as for the initial visa.
This extension will be for a further 2.5 years.
Once you have completed 5 years residence, you will need to apply for Indefinite Leave to Remain (ILR) on form Set(M) meeting all the requirements again including passing the Life in the UK test.
Only once you have been granted Indefinite Leave to Remain (ILR) can you apply for citizenship on form AN on the basis of 3 years residence as the spouse of a British citizen and once you get approval and attend the ceremony, you can apply for your British passport.
It is a minimum of 5 years before you get to the citizenship stage.
There is quite a big fee for every stage you go through.
Your spouse has to meet the financial requirement of £18,600 and provide proof thereof. Your income will not be taken into account as you are applying from abroad.
You need to supply accommodation evidence and provide your spouse payslips, bank statements and letter from employer, etc.