I have copied and pasted the appopriate page of the 2012 SARS guide for employers which deals with deductions for PAYE purposes .As can be seen a taxpayer may claim for certain expenditure actually incurred by him/her against such allowance.However this would not include expenditure for which he has been re-imbursed.Hope this helps.
5.3 ALLOWANCE TO A HOLDER OF A PUBLIC OFFICE
Reference to the Act Section 8(1)(d) and 8(1)(f)
Meaning Any allowance granted to the holder of a public office to enable him / her to
defray expenditure incurred by him / her in connection with his / her office, to
have been expended by him / her to the extent that he / she has actually incurred
expenses for the purposes of his / her office in respect of —
secretarial or duplicating services, stationery, postage or telephone calls;
the hire and maintenance of office accommodation;
hospitality extended at any official or civic function which the holder of the
office is by reason of the nature of such office normally expected to
subsistence and incidental costs incurred.