Yes, they look at any pay that should be owed to you (even if you don't have a snowball's chance in hell of getting it actually PAID to you) and decide how many weeks that (theoretical, often) pay is meant to last you, and they tell you WHEN you can claim.
And even when you DO claim - the first 4 weeks are not paid. Supposedly the new UC is going to sort out that loophole - but I'll believe it when I see it!
I had this when my last employer did a moonlight flit because he couldn't afford the rent increase. I was owed 3 weeks holiday pay, plus redundancy money. JSA took that into consideration, and told me that I couldn't even CLAIM for 8 weeks - and then I had to go another 4 weeks without money.
. So 12 weeks with no JSA.
And at the same time - HMRC fucked up my TC's TOTALLY and didn't pay me for 26 WEEKS. It took my local MP getting involved to sort that one out - .
So, for 12 weeks, the only income I had was my child benefit for my 3 dc. Then for another 14 weeks, all I had was my Child Benefit and £55 a week - it was £10 less a week because I had had two crisis loans while I wasn't getting JSA or TC's.
They are a shower of inept arses at the DWP and the HMRC IMO.