HMRC insist there is no way to avoid being taxed and keep taxing me either £120pm on MBC wage or £160pm on REX wage.
Not sure exactly what was said - you might not be able to avoid tax completely but you can split your allowances as best suits you and hmrc WILL NOT DENY YOUR REQUEST (just say your religion is Jedi and they should be putty in your hands)
note normal allowance is 11850 but your might not be !
If you have standard 11,850 allowance you can request that 7785 is allocated against against REX on a cumulative basis (778 code) and the balance against MBC 4065 (4060) (again cumulative code) with rex being classed as main employment
no tax should be deducted from Rex and tax on MBC i would estimate as being 4541-4060 * 20% = 481*20% = £96 or less than a tenner a month
Note it all depends on your available allowance which is normally 11850 if you have lower available allowance you will pay more tax - so hmrc are not necessarily wrong if you have much lower available.
If you are married and your spouse has more than £700 of personal allowance available - ie income below 11350 they can swap over 10% of their personal allowance to you and that will wipe out your tax - albeit they may have a little to pay if close to the 700 below the pa.
If you are lucky enough to live in Scotland you will benefit from the lower starting rate of tax which might knock £475* 1% = £4.75 off your tax bill - you have to love how they really support the lower earners in that respect