"we were due a refund which we haven't even received yet."
If you got the refund, you probably would have spent it.
Now when the refund comes, it will pay for the tax you are sending by the Dec 31 deadline(s),
since that amount was added to your refund.
If you're like me you have to dig into savings because of no IRS refund yet.
If no savings you can ask for an installment payment plan.
