The ATO advises that it will generally accept that an employee is travelling (overnight) on work,
where all of the following circumstances apply:

  1. The employer pays an allowance to the employee or pays or reimburses accommodation
    and meals expenses for the employee
  2. The payment or reimbursement is not part of a salary packaging arrangement
  3. Where an allowance is paid, the employer includes the allowance on the employee’s income
    statement and withholds tax, where appropriate.
  4. The employee does not work on a fly-in fly-out (‘FIFO’) or drive-in drive-out (‘DIDO’) basis, as
    described in S31E of the FBT Act
  5. The employee is away from their normal residence, at the same work location, for work
    purposes, for a period that is:
    a. no more than 21 calendar days at a time continuously (‘21-day requirement’); and
    b. no more than 90 calendar days, in total, in the FBT year (‘90-day requirement’).
  6. The employee must return to their normal residence as soon as practicable when their
    period away ends.
  7. The employer obtains and retains the relevant documentation to substantiate the fact that
    all of the above requirements are met.
    https://www.ato.gov.au/law/view/document?DocID=COG/PCG20213/NAT/ATO/00001