my spouse (sponsor) is submitting I-864 for me (beneficiary). we did joint federal tax last year and our 1040 tax return form shows combined gross income. we have used same combined gross income amount from 1040 tax form in I-864 part-6 (24.a) . My spouse has enough income without adding my income to fulfill federal poverty salary requirement based on household size. The amount that we included in part 6 - (24.a) is our combined federal gross income and does that mandate me to submit I-864 A form ?
OR will it be better to put my spouse gross income only based on W2 form and not worry about any I-864 A form?

Gross income is whatever you guys filed jointly; individual annual income is whatever your spouse earned

Agreed with @gandharba. You would put the exact amount from your joint tax return in i864 part 6-24. That amount is just for reference. What matters is 2018 annual income. Since your spouse has sufficient income, he/she will put estimated his/her annual income for 2018 in part 6-20 and provide evidences like current paystubs and/or employment letter.

Even if your spouse’s income was insufficient and your income was to be included, you wouldn’t need to fill in i864A as the spouse and intending immigrant but you would need to provide a letter from a employer that your employment will continue after you get your GC. No need to do that since your spouse’s income is sufficient.

current individual annual income should be for 2017( your spouse's W2s only) , since your spouse earned enough , dont worry about 864 A; most people assume current implies current year but it is the most current complete year:

I disagree with @gandharba. Current means current not past. “My current annual income” means annual income for the current year and that’s 2018.

Even if one has zero income in 2017 but say earning monthly 7K since Jan 2018, that person is eligible to be a sponsot for i864 as his/her current annual income is 84K. If one was earning 120K in 2017 but has only earned 2k so far in 2018 say due to layoff, that person will not be eligible to be a sponsor since his current year income is less than the poverty guideline.

You have to submit evidences of current income which is several latest paystubs to prove that what you have mentioned about your current annual income is correct.

You can disagree all you want.
However, if your income in 2017 was too low and 2018 income has convincingly increased above the fpl, then officer might accept 2018 income given that you provide convincing evidence.

You just disputed your own earlier statement. It’s not about disagreeing to someone’s opinion, it’s about laying out the facts and that is the current year annual income is about the present year not past year like 2017.