frangipani

hi
5 year rule, you have been a LPR for 5 years

5 years rule is less headache.
you need 2 passport size pictures, form N400, and check of amount $ 680

They use the tax returns to determine whether or not you have joint finances with your spouse; that's why they don't care about them for the five year applicants.
You should know that while under the 3 year rule they can ask you to prove that you are in a legitimate relationship, under the five year rule they can still ask for you to demonstrate that you were in a legitimate relationship when you got your green card. This has been happening more frequently lately for five year applicants who got their green cards through marriage. So when you go to your interview, you should have some of the "3 year proof" with you just in case.