ATLS is a partnership and you get a K-1. A significant portion of the ATLS K-1 will consist of pass-thru's from APL, so that's just a pass-thru.
But ATLS has operations of its own, and I don't know if those operations show income or losses for tax purposes. I would suspect the operations that ATLS acquired from the old ATLS in February show tax losses, but I also suspect the O&G investment services show income.
And there is a rule that you can't offset losses from 1 MLP against income from another MLP, even if they are related. So, my K-1 from ETE last year showed separate income/loss for ETE and each of its MLPs (ETP and RGNC). Same thing for EPD/EPE. So maybe ATLS K-1 will show the APL stuff separately. Very confusing, but at least the investment is working out well so far.
They are taxed the same but APL holders have more income sheltered from APL account the IDR's do not come with the offsetting depreciation ect. Most likely when APL starts kicking out lots of money then ATLS will be passing through more taxable income to holders than APL. Both are still good buys but ATLS has more natural gas exposure. With gas prices very low there will eventually be a time when ATLS's natural gas reserves add significantly to it's value.