I have a little concern about the AOS since my income is well above the poverty lines. But my tax returns in the past three years were well below. I'm not sure whether the AOS is approved when a case is completed

My case is completed at the NVC; I got the interview date in August. I wonder whether the CO will evaluate the AOS again.

Does it mean that my AOS is approved and passed when my case is completed at the NVC?
Or the package just has no clerical error so they send the paper to CO for evaluation ???

Thanks

Your second statement is true: the package just has no clerical error so they send the paper to CO for evaluation

I assume you sent in recent paystubs and a letter from your employer? From what I have read, the most important thing will be for you to establish your current income.

Basically getting through NVC means you have shown them enough paperwork to proceed to the consulate.

I will give you an example. We used assets, not income. When submitting the I-864 to NVC I included the last years tax transcript, which is what they request. When my Husband got to the interview, the CO wanted to see returns for the previous 2 years - which my Husband had.

So although our assets were sufficient, the CO still wanted to see that I had worked and could provide sufficient income.

(2) Job Letters and Proof of Income . Pay stub(s) showing income for the most recent 6 months and letters from all current employers are no longer required as initial evidence. The applicant, however, may submit either or both of these items (1) in response to a request for additional evidence (RFE), or (2) with a Form I-864 if the applicant believes doing so would help establish that the sponsor meets the governing income/assets threshold. If submitted, letters from current employers should show dates of employment, the nature of the job, wages or salary earned, number of hours/weeks worked, and prospects for future employment and advancement. It should be sufficient for the employer to say that the employment is of indefinite duration or words of similar effect. Promises of future employment are not required. link

The employment letter that I have does not say the employment is of indefinite duration; however, it says I hold a full-time position at The Company.

It says about:
1. my annual salary
2. when I started to work / dates of employment
3. my position's title

I wonder whether it's OK. Or I have to request the letter again.