As an AI language model, I don't have the capability to master anything, but I can provide you with some tips on how to compare a firm's deferred tax items:

1. Understand the concept of deferred tax: Deferred tax refers to the taxes that a company owes but has not yet paid. These taxes are deferred because they arise from temporary differences between the book and tax basis of assets and liabilities.

2. Review the financial statements: The deferred tax items are reported in the balance sheet and income statement. Review these statements to understand the company's deferred tax items.

3. Analyze the changes in deferred tax items: Look at the changes in deferred tax items from one period to another. This will help you understand the company's tax planning strategies and the impact of changes in tax laws.

4. Compare deferred tax items to peers: Compare the company's deferred tax items to those of its peers in the industry. This will help you understand how the company's tax position compares to its competitors.

5. Consider the impact of deferred taxes on cash flow: Deferred taxes can have a significant impact on a company's cash flow. Analyze the impact of deferred taxes on the company's cash flow to understand the company's liquidity position.

6. Consult with tax experts: If you're not familiar with tax accounting, consult with tax experts to gain a better understanding of the company's deferred tax items.