For a couple with no dependants the minimum gross income needed is £18600
For those on specific verifiable benefits there are possible exemptions.
May I suggest you review this thread
How to apply for a Spouse Visa which may help your understanding.
As mentioned, even under exemption conditions it is still is required to demonstrate that there will be adequate maintainance to support yourselves without recourse to public funds and without relying on promises of third party support.
In principle ‘adequate maintainance’ means that after housing costs have been deducted, there must be a level of income available in line with levels of income support.
Please be aware that the need to comply with the financial requirements will need to be demonstrated at each stage of FLR/ILR application in addition to the Visa Entry.
With this in mind you should seriously consider how the Government’s welfare reforms may impact you.
The new reforms include the introduction of Personal Independence Payment from April 2013 and the roll-out of Universal Credit from October 2013.
In particular, before April 2013 the Government will review the treatment under the financial requirement of disabled people and carers, with a view to ensuring that the basis for and operation of the financial requirement properly reflects the Government’s welfare reforms. Any changes will be announced in due course, but an applicant – sponsored by a person in receipt of a specified disability-related benefit or Carer’s Allowance – who will be exempt from the financial requirement from 9 July 2012 cannot expect that they will necessarily remain exempt from April 2013.
