Imputed Interest - strange situation

[Gretel]

Client buys a lot for $50,000, turns around and sells it for $60,000 to spec home builder. Closing statement says sold for $60,000. However, buyer has until half a year later to pay full amount. If he can't pay then daily interest will be charged.

I am concerned about imputed interest but have no clue on what amount to base this on. Normally you don't calculate imputed interest "backwards", meaning starting with $60,000. Obviously interest is calculated in total amount they agreed on would be selling price.

Any thoughts?

[Burke]

Interest would be charged on the amount outstanding after 6 months, whatever that may be. Did he receive any funds at all? If so, that would be principal (down payment). Assume it was sold in 2010?

[Gretel]

Interest would be charged on the amount outstanding after 6 months, whatever that may be. Did he receive any funds at all? If so, that would be principal (down payment). Assume it was sold in 2010?

I am fine with what happens after 6 months. No funds were exchanged at closing. Can someone sell a property with a postponed payment date (6months) and not have any interest income?

The sale just happened. This is a client I do bookkeeping for and want to put it on the books correctly.