Income-related ESA form query

My partner previously got Incapacity Benefit and was moved onto contribution-based ESA. He has received a letter and form ESA3(IBR) 06/18 saying he may be entitled to income-related ESA from 2013. I am confused about how to fill in some of the questions.

It asks for bank balance etc but I'm not sure when they want the balance for? Is it the balance now, what it was in 2013, or all the years added together? There is only one box on the form to put the info in. He doesn't have bank statements going back that far so can't provide evidence of the bank balance going back to 2013.

Similarly it asks for how much cash we have. Is this how much we have today, in 2013 or for the past 5 years added together? There's no way we can provide evidence of that information.

Is the form compulsory or can we just ignore it? Neither of us have savings over £16,000 and don't work more than 24hrs a week so can't tick any of the 3 boxes saying he doesn't want to be assessed.

Thanks for that Gordon, looking at that it looks as if he may be entitled. However I still don't think we can fill in the form as we don't have bank statements going back to 2013 and I'm still not clear how many years to give information for, as there is only one box to write a figure in. I'll just have to write to them and say we can't fill it in because we don't have the information they want.

I may be wrong, but if during the period your savings have never exceeded £5500 then no proof is required