UN completed the construction of a school building on $1$ January $2013$ at a cost of $$1,000,000.$ The building had a useful economic life at that date of $40$ years. On $1$ January $2020,$ UN revalued the building to its current fair value of $$1,200,000.$ On $1$ July $2020,$ a major upgrade to the building was undertaken at a cost of US$ $50,000$ which is higher than the capitalization threshold as per UN Property, Plant and Equipment policy. UN Financial year end on $31$ December. As the Head of Field Finance, propose all the relevant accounting entries for the above transactions in $2013$ and in $2020.$ State any assumptions made.

QUESTION $4($b$)$: The Deputy Director of Finance would like to get your professional advice regarding the impact of this transaction on the current and prior year UNRWA Financial Statements. UN uses IPSAS reporting framework and its financial year end on $31$ December $2023.$ A recent review of the useful lives of fixed assets indicated that the useful lives of fixed assets in UN should be revised to ensure UN$$s Financial Statements remain faithful and reliable. Analysis indicated that the required revision would increase the useful lives of all Fixed asset categories. If the revision happens effective $1$ September $2023,$ UN would like to understand your advice on how the accounting entries and disclosures from this useful lives revision will impact the current year$$s and prior$$s year Financial Statements.