Answer: April 2024
Step-by-step explanation:
Based on the information given in the question, at a minimum, the appraiser must retain his workfile till April 2024.
It should be noted that appraisal records should be kept for at least a period of 5 years. In a situation whereby there is a report which is involved in the litigation, then such file must be maintained for a further two years. This is according to the Uniform Standards for Professional Appraisal Practice Record Keeping Rule.