Answer:
Debit deferred tax asset for $12,000
Debit income tax expense for $18,000
Credit income tax payable for $30,000
Explanation:
The journal entries will look as follows:
<u>Date     Account Name and Description       Debit ($)      Credit ($)   </u>
20X1     Deferred tax asset (w.1)                        12,000
              Income tax expense (w.3)                    18,000
                 Income tax payable (w.2)                                      30,000 
<em><u>             (To record income taxes at the end of 20X1.)                             </u></em>
Workings:
w.1: Deferred tax asset = Deferred portion of the rent collected in 20X1 * Tax rate = $40,000 * 12% = $12,000
w.2: Income tax payable = Taxable income * Tax rate = $100,000 * 30% = $30,000 
w.3: Income tax expense = Income tax payable - Deferred tax asset = $30,000 - $12,000 = $18,000