Hello weesie81
The only sensible thing to do in a situation like this is to come clean with a full and complete disclosure to ALL the relevent bdies that have been defrauded.
If she does not provide full and complete details then she will probably always be worrying if another public body/the same public body will come back a later date and start to dig deeper than they have done as of yet.
Anything short of a full disclosure will be looked upon in a very bad way by a judge or a n other if there is to be any leniency shown.
An unsolicited full and frank disclouse is also much better than a forced full and frank discoluse so don't wait till the last minute to come clean.
After this is done she can then take whatever punishment is handed out and carry on with her life in the knowledge that she will not get into further trouble at a later date.
As a priority she should probably also seek legal advise and follow this is closely as possible.
she does not want the small cleaning company to get into any trouble either even though they knew what she was doing?
I would not worry too about the cleaning company to much in a situation like this,they have made their own choices and will have to deal with the consequences as things pan out.It sounds like they are the more innocent party here if your mother has gone to the trouble of using a fake name and fake ni number.There should not have been any "cash" saving for them using one name over another - although it may have been easier from an admin point of view if she was paid gross rather than net - with the deduction being passed to hmrc.
It may be that if her earnings are below the tax threshold - say an average of £100 per week over the last few years - then there may not be any/much loss of tax but i suspect from a legal point of view using a false name is a quite serious offence.