by the way. if you deducted these in a previous year, you can't deduct them again.
many schedule C taxpayers can and do use the cash basis method of accounting. income is taxable in the year received and expenses are deductible in the year paid.
say you do use the cash basis. in 2017 you buy a faucet but you don't use it on a job until 2018. it should be expensed in 2017. and so whatever you get from customer in 2018 is fully taxable. you can't deduct the cost of the faucet again.
