I hope this is not too daft a question but could someone let me know how I can work out someone's applicable amount once ESA comes in?

CPAG website should help you. Can i also plug our ESA guide which will explain ESA in depth, available from mid-October.

Thanks for the links which are helpful, however our concern is that we do alot of benefit checks at the moment which involve working out if someone is entitled to a top-up of income support or to work out someone's housing/council tax benefit entitlement. This is straightforward at the moment as we can use the Income Support rates to work out people's applicable amounts based on their circumstances/DLA awards.

However under ESA once someone is in the main stage the amount someone gets depends on wether they are in the support group or the work group, therefore where we have clients who have another income other than IS/IB such as work-related pensions or who work but are entitled to DLA which rate of ESA are we using to work out their applicable amount?

Unless they can obviously be treated as not having limited capability for work and/or limited capability for work-related activity then you can't know which group any claimant will be in until the DM has made a decision.

In some cases you can could make an educated assumption by applying the descriptors yourself, but given that in the test application of the work capability assessment many assessments were found to to be false-negative (failed when should have passed) this will be somewhat hit and miss.

I suppose the solution would be to do both calculations at the same time or just do in based on the work-related activity group which would give a minimum figure (assuming the LCW assessment is passed).