As a cash based taxpayer you can only deduct in 2021 what you actually paid in 2021. If you put this on a CC then it is considered paid even if you did not pay off the CC yet. If you wanted to deduct the expense in 2021 then you should have had them bill you in 2021 and paid the invoice in 2021. If they did not get the payment in 2021 then they will not report the income in 2021 so you cannot deduct the expense in 2021 ... does that make sense?
