Almost no one provides a credit any more. If it's in a customers tank, we can’t guarantee what's in it. It gets recycled, not re-used and that costs money.
Give it to a farmer or someone else who heats with oil. If the tank was disturbed before/during draining It likely has sludge and particulate stirred into the oil and will need to be left to settle before someone uses it.
I hope you didn't switch to propane. If you did, I hope you pre-bought for the upcoming winter.