So, for your documents you need:
Applicant
- FLR(M) application form
- appointment confirmation/payment receipt
- IHS payment receipt
- your current US passport
- 2 passport photos with your name on the back
Sponsor
- his UK passport
- 1 passport photo with his name on the back
Finances:
- 6 full months of sponsor's original payslips showing at least £1,550 per month before tax
- 6 full months of sponsor's original bank statements showing the deposit of every single payslip
- employer letter stating job title and current salary, length of employment, length of time earning current salary, type of employment
- original job contract
- latest P60
Accommodation:
- Land Registry document
- latest mortgage statement
Relationship
- marriage certificate
- any divorce decrees from previous relationship
- 6 items of official correspondence addressed to both of you at the same address, spread evenly over the time since you arrived in the UK
- if you cannot provide all 6 items, you need to write a letter explaining why not