HI Ant,
This is a great question!
I have a couple of thoughts on this...if someone misses their deadline day, their legacy benefits would run on for 2 weeks from the deadline day and then stop. Even though they could claim UC say three weeks after the deadline day and still get transitional protection, it could mean a gap in income since their legacy benefit run on would have ended and they'd still have to wait the usual 5 weeks I think for the claim to be sorted out.
My second thought on this is that if you don't ask for an extension and then something comes up that causes a delay, there is a risk of missing the final deadline day and that's a really big problem, as you will have seen from the guide.
So I would say if someone knows they may struggle to claim by the DD, then they would be best to ask for an extension just in case to minimise anything going horribly wrong.
Best wishes
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