relevant documents to be attached with my N400

[leapoffaith 0]

As I understand, these are the relevant documents to be attached with my N400 for documents referring to me and my spouse :

Tax returns, bank accounts, leases, mortgages, or birth certificates of children, or

Internal Revenue Service (IRS)-certified copies of the income tax forms that you both filed for the past three years, or

An IRS tax return transcript for the last three years.

We don't have children, is there anything else to be send with the form ?

[H&V 5]

I think you have already but take a look at the USCIS checklist and find out what you have to send that applies to you. But yes, for the documents referring to you and your spouse, what you highlighted is correct. Note the word 'or' at the end of each line - I say that because most folks find it easiest to order the tax transcripts online and send those, since it saves on having to gather evidence and worry if you are providing the right stuff. The tax transcripts are an easy alternative.