There seems to be some misunderstanding about what an “expenses payment” actually is.
If you are a toff claiming expenses, you’ll actually be given an extra sum of money which can be spent on things like upgrades to first class travel, fancy hotel rooms, expensive restaraunt bills, and the like. If you don’t spend the money on these things, you won’t get given it back as a cash rebate.
For middle class people claiming expenses, the system is pretty much the same as for working class claimants. You put down expenses directly related to doing your job. Having the presidential suite instead of a flea pit room in a hotel is NOT essential to your job, unless it’s nobbing with other high ups (which alas it often is!) so the likes of you or I would never be allowed to claim for such things.
Fuel, Meals, Overnight stays in accommodation, work clothing, and tolls are the most common things working folk claim on expense forms.
They, however do NOT get given “cash to the equivalent of” out of the firm’s pocket, nor the clients. It is a tax offset which means less of your gross pay is taxable than would be otherwise. I’ll say it again: The taxman gets to charge tax on less of your gross pay than otherwise would be the case.
Eg. Earn £330, tax offset £130, leaves £200 taxable, of which £160 further is deducted as your “tax free allowance” from your tax code, assumining it is just above £8k per year (L816) as mine might be. Thus, you end up being fully taxed on the princely sum of about £40 of your £330 wage packet, which is less than a tenner. However, I do have to actually incur the expense. Most of what I claim personally is mileage, so I prefer working at locations far away but easy to get to (eg. a few miles down the motorway using the nearby linkroad to get onto said motorway, without having to drive through rush hour traffic in town…) Because where I live and where I work are known documented details, the taxman won’t be asking me for any money back that has been “overclaimed” because it won’t be in the first place! 
Play it straight therefore, and be rewarded.
I rarely pay tax with the work patterns I work, but that doesn’t stop me from taking home a net £18k for the year, based on the same work patterns as I had last year. I’m not a scrounger for doing this, any more than I’m a scrounger for denying umbrella firms from charging me their “fiddle fees”.
There’s not much point me going self-employed though, because may tax due won’t ever drop below zero, and it’s pretty close to that already.
IF I were being paid what I called a ‘toff’s expense’, (actual extra pay for things like jet travel) then it WOULD then be worth going self-employed however. I believe BBC staff have been busy doing these for some time, which has come to the public’s attention.
I still believe that £18ph is the minimum amount I’d invoice to make it worth my while going self-employed, with the lifestyle of expenses that I have. 
AS we all know, the market won’t stand that as it is, but maybe one day in the not too distant future?.. 
If your car runs for less than 45p per mile, you’ll be making a profit out of tax-offsetting it of course. That’s the attraction of the whole damned thing more than anything else! Meals will only get you what you spent in McDonalds, or wherever. Clothing, Tolls, & Accommodation ditto.
MILEAGE is where the money can be made - IF you have a vehicle that’s cheaper than 45p/mile to run.
Well? - Do you all?
C’mon let’s see some willies flopping out here! 
) than £10/hour on PAYE or you were fiddling the Taxman 
