Other than buying stuff and getting gifts, what does SS like?  Does he play video games?  If so, take away the video games until he's done with homework, but if he finishes all his homework for the week, and turns it in (as verified by the teacher), he gets extra time.  Carrot and stick.  Is the reason he doesn't like doing homework at school because if he does it at home someone will sit with him and help him - i.e., do his homework for him?  If that's the case, then I'd think the excess help has to stop or he has to stay in the homework program.  I have ADHD and hated doing homework and my parents took the carrot and stick approach - both punishment and rewards.

I was told with my adhd son that positive reinforcement works and I had the same doubts as you. I mean, it does seem like they would expect candy or whatever every time they do that task right? But it actually did work, at least for my kid, that once he was in the habit of something the rewards weren't as necessary anymore. For instance, he used to get one for doing his morning routine and getting ready on his own (he was like 7 I think at the time). He still gets ready automatically on his own every morning now and we haven't given him anything for it in a long time. 

Also, I he might need help with some study skills that seem obvious to others. I guess for kids with ADHD planning out "okay, first I do this step and then this step" and so on can be difficult. Maybe also help with breaking down tasks into smaller chunks so they're not overwhelming. Google or ADHD books probably could explain helping with study skills better than me.

We sent SS to Military School for just these reasons.  There are a few schools that take 7th graders.

Play the Military School card and he will never miss turning in another assignment again. 

This was my SS to a T when he was 12, avoiding homework, lying to both home and school about it.  My DH was strict and BM was a coddler.  She would hold his hand, be his scribe, or even do the homework for him. Needless to say, DH became the Big Meanie and SS stopped coming over or speaking to DH at age 15.  From there on out, the school put him in an alternative program, BM allowed him to stay up all night gaming and do whatever he pleased. The school pushed him through to graduation because they were sick of him, I'm sure - and now he's 20 and literally doing nothing with his life (at BM's). He's lazy and unmotivated about everything he does.  I don't think he was ever even formally diagnosed with ADHD, though IMO, he definitely has it.

Anyway, if your DH and BM are going to coddle and baby him, this will not get better.  Rather than put SS on notice that he's out at 18, I'd put DH on notice that I'm not moving anywhere with SS in tow because he's failing at life and still dependent on his parent. 

Research adhd or talk to an adhd coach/therapist and build strategies that work for your ss. It may take trying lots of different things before you find the combination that works or you may find a list of things that work for a bit but then they need changing around every so often.

In my mind positive reinforcement is the way to go. Kids with ADHD are told that they are useless, lazy and lack "willpower" enough. They are told that they just need to "try harder" or that they just need to "get it done".  It does not help with anything but destroying self esteem and reinforce negative self images. When you are told that you are useless you feel useless and feel there is little point in trying.

The real issue is that have a problem with the way their brain works that makes it difficult to start tasks, difficult to concentrate on tasks and can make it feel like tourture to do simple, basic things amoung numerous other symptoms. What is needed is a real understanding of the situation by both the child and the adults around them and then changing the way the problems are viewed and the way they are tackled. 

Obviously when I say "you" in the above writing ideally this would be the boy's bioparents who are leading these efforts...

Teacher here.

From my experience in a absoultely RABID district for 5 years.

The only prescription for an ADD diagnoses (a kid who can't or won't focus), are parents who are willing the drop the entire hammer. Even with an IEP, the most intensive interventions done in public schools require the teacher to prompt (to tell) your kid to do the work. Yes, IEP is a legal document, but no, they don't expect classroom teachers (after elementary) to coddle.

You can't reasonably expect a teacher with a classroom of 35 to completely re-teach a lesson to just your kid, and have time to fulfill the needs of the other 34. Sometimes there's an instructional assistant in the room, but I can tell you that 90% of the time there is not. There are just not enough hours in the day or minutes in a class to accommodate past the point of recognition.

My best suggestion to you (if you care), buy the kid a planner. Call his IEP case manager and have her mass e-mail his teachers to please ensure that he writes assignments in the planner daily. Also, you're going to have to re-teach everything from every day from the notes he brings home. Every day. Especially when he hits more difficult (7th grade math.

If not, they'll just pass him on since he has an IEP, and he'll remain at about a 5th grade math level throughout high school. If teachers stay after school for him now to tutor for free, take advantage of that, but do not expect that every year you will have teachers that have the time or the desire to teach twice.

Not guaranteed to work but might help. In addition to making him earn his privileges, he may know how to do something but not know where to start. 

He may need 

“ I expect you to complete the introduction of this essay in the next hour, up the kitchen table where I can see you. These are your resources. We will come back and help in an hour and see what to do next”.

BTW there are tons of videos on youtube which explain adhd and have suggestions to help both parents and kids. Watching a few of them with your husband and your ss could help find some good strategies to try out. Involving ss in this is good to get his by-in and help him to learn how to help himself with some support from those around him.  

Does this include a parent who uses the adhd meds for a buzz????

Asking for a friend.

SS was diagnosed with ADHD when he was maybe 4 and again at 13.   In truth, he has auspergers.

Regardless, he was never held accountable at BMs for anything, including HW!  He literally did nothing.  He moved in with us at age 13, and despite laying down our expectations with him, spending COUNTLESS hours helping him with his HW (not doing it for him, of course), and everything else we could think of, to this day as a SR in HS, he often opts to do NOTHING and is irresponsible, and downright lazy in all aspects of his life.  And yes, he too would and will lie about his HW. 
 

We tried both positive and negative approaches, to no avail!  He too was prescribed various meds over the years and either will not take them at all or took them so sparingly we could never discern if they would have been helpful or not. 

I would STRONGLY  recommend he stay with BM! Save yourself the nightmare I've been dealing with the last 5 years.   If he's allowed to live in your home, you may likely end up with a kid that doesn't want to launch and a DH that won't force him to, in addition to YEARS of being miserable in your own home and a relationship that suffers because of it. 

Just Noooooo!  Tell DH that SS would perform even worse in your home, adjusting to a new environment, new lifestyle, new routine, new school etc would be worse for him!  

SAVE YOURSELF !   

Wish I had...
 

Mom and teacher here. Unfortunately in my experience there is not much aside from doing it together. Rewards and punishments don't work that well. Break up hw into a very small chunks and check in after every chunk.