cp_acwt wrote:The definition of the cash basis of accounting is that you record revenue when cash is received, you record expenses when cash is paid. [...] In your example, if the merchandise is not paid for until 2019 the expense is not recorded until 2019.
But, we have the matching principle: "The matching principle is related to the concept of revenue recognition. The matching principle states that both the revenue and the expense related to the same transaction should appear together in the same accounting period. For example, if a business sells a product, the cost of goods sold related to that product should be recognized in the same accounting period in which the revenue is recognized." [CE material]
cp_acwt wrote:the question started as an accounting theory one and turned into balance sheet presentation on the income tax return.
With the full cooperation and encouragement of the OP.
The practical question might be, how to record the receipt of the "merchandises" in the double-entry books. If they were paid for via credit card, I think we all know the credit card liability would be recorded along with the asset. If not, maybe we look to the "freight on board" rules and all the other stuff about when title to the property actually changes hands.
But there is nothing wrong with recording the transaction in 2018 on the company books, and then showing it as "Expenses recorded on the books not deducted on the return" for tax purposes, and then showing it as a 2019 transaction for tax -- if, as noted above, there was no revenue recognized from the asset in 2018.