Going to keep this short and sweet as I have a few questions. I'm a recent uni grad so my knowledge and expertise on tax isn't the best but here. I've read up on all the WFH deductions for utilities and such. But I just wanted to ask how deductions work.
a) Lets say Im earning 80k a year and I buy a new standing desk that costs $800. Since I work 9am-6pm (9 hours) and then from 6pm-10pm I'm on my computer for recreation, that means I use my desk for 70% work related purposes. Am I able to use the prime cost method to depreciate the asset over 10 years? So over 10 years, I will be able to deduct 70% * $800 of the asset from my ordinary income.b) If I buy a $250 dollar chair (solely for work use), will that reduce my taxable income to $79,750 since it is under $300?c) If I buy a second hand chair from Gumtree/Facebook Marketplace for $1000, will I be able to deduct it from my income? (If so, how since there is no record)