Income Related Support Group ESA to UC - Letter Received Taxable income

Hi,
wonder if anyone can advise me on a letter I received from Jobcenterplus.

Firstly, I am week 4, of the mandatory transference from Income related Support group ESA to UC.

I received this letter which maybe standard, however I am confused about it, since I was on Income related ESA, which I understand is not taxable (Income related (means-tested) ESA is not taxable). I was on contributory ESA when I first received ESA in 2010 which as a result of my disability went to Income related.

Basically, the letter states:

"We are writing to tell you that the contributory element of the Employment and Support Allowance can count as taxable income.

For the period up to 20 May 2025 in the 2025/26 tax year we paid a total allowance of £1038.66 of which £0.00 was taxable. This is added to any earnings for this tax year. "

Now of course it says, if I think this taxable allowance is wrong to contact them.

1. Is this letter saying they think I was on contributory based ESA?

I am at a loss as to why they think my allowance was taxable in the first place, (or whether this is normal procedure when coming off ESA, and they're back dating this to the very start i.e. 2010? Which doesn't seem logical since it's over a decade and a half ago)

2. What that figure of £1038.66 relates to? It's not benefit from (tax year start) 6th April - 20th May 25.

3. Should I contact the jobcentreplus to query this?

I only have a specific time frame of 60 days to challenge it or correct it, and I am due to find out what I will be getting on 9 June 25, and I thought I better do this before, if there is an error that might affect the UC claim.

4. Lastly, would I then have to self declare this figure as over £1000 in 25/26 tax year?

Would appreciate any advice and if anyone can shed some light on this letter and what to do.
TX in advance

Yes, I did get a P60 and a P45 too.

The £1038.66 was on the letter, and I have no idea of where that figure comes from (not on P60)or what it is pertaining to.

Okay, thank you. The P60 has zeros in the totals, and every year I have had a P60. I used to be self-employed, and still do tax returns, regardless of no income from self-employment, could this be the reason for the P60, if others are not getting the same?

As I understand it:
"Contribution-based ESA:
If you only receive Contribution-based ESA, you are not part of the managed migration to Universal Credit",

Yet I am, and my paperwork from Jobcentre Plus, says so, I also received my managed migration, so I am totally confused.

I guess I need to contact them, from what you are saying.

Appreciate any additional thoughts on this.
TX