Is amount on Q23 (I-864) before or after tax

[WorldTravelers 5]

I posted this question in NVC thread and after 57 views had 0 answers. So, I am trying in this more general forum.

Which of these should be the answer to question 23:

1. Gross pay from W2. <br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);">2. Amount from the employment letter, which lists annual pay. <br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);">My employment letter, shows ~$500 less than what's listed as GrossPay on W2 (I guess that's their estimate before W2 was ready). Is that a problem or should I have them make another letter with exactly the same $ amount as Gross Pay?<br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);">3. Amount in Box 1 on W2.<br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);">This is net pay, the same as on question 7 on 1040 for year 2012. <br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);"><br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);">On question 25 I will put the AGI from 1040 for the last 3 years.<br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);"><br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);">I only have one W2, I am the only sponsor, and the household size is 1 (+ the intending immigrant, my mom). <br style="color: rgb(28, 40, 55); font-size: 13px; line-height: 19px; background-color: rgb(250, 251, 253);">Although my income well exceeds the poverty guidelines, I will also be including the assets in Part 7 of I-864, for just in case since I am sponsoring my mom, a senior, and I want to make sure I prove she'll not become a public charge.