Anna works as a nurse in an aged care home. She bought a box of five COVID-19 tests for $50. Anna used one of the tests to confirm that she did not have COVID-19 before visiting her parents. She used the other four tests to confirm that she did not have COVID-19 prior to attending her shift at work. Although her employer requires her to undergo a COVID-19 test prior to commencing a shift, the employer does not provide COVID-19 tests or reimburse Anna for the cost of the tests. Advise Anna as to the deductibility of the $50 incurred on purchasing COVID-19 tests.