To expect my very bright, autistic kid to not fail his SATS?

I'd he doesn't want defenders, my DC like the loops but you may need to request to the exam board he can wear them

My autistic DD is also academically ahead ( possibly not as far as your DS) but needs extra time in exams as she has a slower processing speed. She also sits them in a separate room with a small group and can have movement breaks when she needs. She’s only year 5 now so not doing formal exams, but this helps and will be in place for her SATS.
it’s not clear if the school you’re looking at is academically selective, but we ruled out grammar school for DD as between the slow processing and the pressure it would be too much for her. Selective schools move fast (DS is at one so I know) and don’t have lower sets for those who are struggling.

Your DS is only in the 1st term of Y6 and most children at this stage don’t score as highly in their SATs as they do in the actual assessment. Give him a break!
Also, there’s no pass or fail, just a raw score and standardised score with Greater Depth, Expected and Below Expected reported.
I’m curious though - how come he no longer uses ear defenders now he has a diagnosis?

Have you asked your son? He will presumably have some insight into how he did and what the issues were.

The reasonable adjustments have to be something that have been used previously not just for final tests.

Schools do assessment tests regularly, how has he done in them in the past?

Key stage 2 test administration guidance - GOV.UK https://share.google/r7EDc8FAMACXmf3OS

Found it! If you scroll down to 7.3 the separate room part is covered.

Have all his siblings got scholarships already?
It seems a lot to expect to send all your children privately and have it subsidised by bursaries

DS1 is autistic but also has OCD and gets anxious and obsessive about tests. Did extremely well in SATS and grammar tests. I spent years reading to him and with him as I felt strongly his inference skills needed help, not just for exams but life in general.

2026 key stage 2 access arrangements guidance - GOV.UK https://share.google/wjlaC3H8Idvtyt1YO

This is the school guidance.

Have you looked at the papers? The reading and maths reasoning ones aren’t a walk in
the park . What are his inference skills like? Can he apply maths skills?What is his focus like? ASC and ADHD can go hand in hand. ADHD can have a huge impact on SATS.

Private schools don’t care about SATs. They don’t do them. Presumably he has already taken an 11+ exam and his place will be confirmed shortly.

My eldest is High functioning ASD and super bright. 10 grade 9s at GCSE etc. In Y6 I wasn’t thinking about SATs at all. I was thinking about his social skills, executive functions and how he would manage a transition from a tiny village school with mixed year group classrooms and a world in which he’d known everyone since Reception or playgroup, to a big senior school further afield. He’s now at an even bigger sixth form college and really thriving.

ITA too. Poor working memory can also go hand in hand with other types of SEN, such as autism, ADHD, dyslexia, language disorder, etc.

Was DS achieving in line with his high intelligence in the classroom; and the SATs results have come as a big shock? Or was he underachieving in class, before the SATs?

Oh my goodness, this sounds like the sort of thing that used to happen to (autistic) DH.

More positively, he got over 100% for one of his Science O levels because he was bored so re-answered one of the questions using a different method...

I am a bit unsure how you think the SATS wil relate to a bursary for private school. Where I am, the private schools hold entrance exams in January (way before SATS in May) and scholarships and bursaries are considered based on the results of these. By the time SATS are done, secondary places are already determined.
Is your son doing an entrance exam?

Which SATs - all of them? My very bright autistic child struggled with the reading, despite being a decent reader - in part because there’s questions that require things like inferring feelings or motivations - “why did X do Y?”, my child responded along the lines of “I’m not X and it doesn’t say why so how would I know”. They also struggle with things they don’t see the point of, so large swathes of the grammar paper they struggled to do because they were so cross at being asked to do something so pointless.

Have you asked for copies of his mock papers? I read my child’s papers which was quite illuminating and we were able to work on some things at home. I also focused on maths and reading - huge parts of the SPAG paper are deathly boring and, bar spelling, of very little use later on.

Child did sit the papers alone in a quiet room which helped enormously with distraction - because this was a fairly common adjustment for them anyway in their day to day work school didn’t even need permission, it’s regarded as their normal way of working. It does require a room and spare adults though which I imagine some schools might not have.

Agree with fxl on this. If he's generally doing well at school, but got a low mark on the SATs, it suggests there's something worth investigating.
It's fairly common for autistic people to have a slower processing speed, for example, which would definitely have an impact on timed exams.
It would be good to know his exact profile so you can work out what kind of support is needed.

DD is 19, ASD, very bright … had I know what a terrible effect those end of Primary School SATS would have on her self-esteem and confidence, I would have withdrawn her.
Having to go to “extra lessons” for English, led to years of believing she was “terrible at English”, and I honestly believe it’s partly what led to Aniexty, EBSA, and missing Y10&Y11

You can choose for him not to take them.. seriously consider it.

You might find it helpful to get an educational psychologist’s report, which should do an independent assessment of your child’s learning abilities/profile and suggest the reasonable adjustments which should best support him

Just my experience.
I'm autistic and in my fifties.
When I was 7 we did county-wide Maths tests and my results showed me to be what was then called ESN (educationally subnormal 🙄). I was made to repeat rhe test and the same thing happened. Then my mother instructed me to answer the questions exactly as they appeared and not overthink them. On the third attempt I got the top results for the county.
Apparently I thought for some reason that the questions couldn't possibly be straightforward, and so made up my own methods of answering them.
I.would get him to practise answering test papers with you, checking he understands exactly what they are asking. Standardised tests don't seem to be designed for nwueodivergsnr thinkers.

I agree with @BusMumsHoliday . My eldest had a lot of trouble with GCSE English Language 'why did the writer ...' sort of questions. i had to teach her a process for some questions to blindly follow to come up with something.

You can teach children to understand questions. Sometimes autistic kids need very specific, atypical instructions. My much younger DS can struggles with "what do you think will happen next?" questions, and he'll say "I don't know" - because in his head, how can anyone know what will happen next, it's not a recall fact. But what helps is explicitly reminding him that he's not expected to locate this information in the story. In time, he'll learn that this is what the question wants him to do, even if that leap is never innate.

You and the teacher need to work out what is going on in the mock tests. Is he sitting there doing nothing (which may not be not trying!) or is he getting answers wrong, misunderstanding questions etc?

I have a very bright much younger autistic child. Sometimes he'll get so fixated on a mistake he's made or the possibility of a mistake, that he literally can't continue with the work. Other autistic children will misinterpret questions, or zone out and need prompting, or need help allocating time to individual questions. You might be able to put special exam arrangements in place to help.

My son is sounds so similar he is academically very bright, autistic and socially young. He is now in year 7 but he found all of year 6 so so hard emotionally.

He also took every stats pep talk to heart and got anxious. For him the changes to the classroom for mock stats ( covered display boards, moved desk ect) really ramped his panic. In school his was the same eager student but late at night at home he was so distressed.

For him what worked was taking the papers in a different room in a small group. Also a bit more practise of how to read stats questions and learning good exam technique was helpful. At home we removed any pressure and reassured him that as long as he did his best all would well.

Sounds like you need to work on exam technique. Speed is tricky. We've had 11+ to get through with my Nd DC and while the content was fine doing that content 30 seconds per question was a steep learning curve!