Owner wants to redeem tax lien

[Kee Wilder]

I received a certified letter for verification of Allowable expenses by tax sale purchaser from Jefferson County AL. I bought a tax lien property earlier this year from someone who purchased a house at an auction. I've invested money into the property and i'm literally a month away from renting it out. I've stopped the contractor from making repairs to the property. I just received the letter Saturday (two days ago). What do I need to do to inform the owners that I need to be reimbursed for improvements made in the home? Is there an example template or letter that I could follow to send to them? Do I need to show receipts? Much of the work was done by myself or family?