REG coverage of book-tax differences, M-1 and M-3 adjustments, and common corporate reconciliation errors.
This chapter explains why financial accounting income and taxable income diverge and how those differences are reported. REG questions in this area often test whether a difference is permanent or temporary and how it should appear in a reconciliation.
The key is to track whether the difference reverses. A temporary difference affects timing between book and tax income, while a permanent difference affects one system but never reverses in the other. Entity reconciliation questions often become manageable once the candidate labels the difference before calculating.
| Difference type | Reversal expectation | Common REG trap |
|---|---|---|
| Permanent difference | Does not reverse in a later tax year. | Treating nondeductible or tax-exempt items as timing differences. |
| Temporary difference | Reverses because book and tax recognize the item in different periods. | Forgetting that reversal affects later taxable income. |
| Depreciation difference | Often arises from different book and tax recovery methods. | Comparing expense totals without tracking accumulated timing effects. |
| NOL or limitation item | May require carryforward, limitation, or separate schedule treatment. | Assuming a deduction is fully usable in the current year. |
| Step | What to identify | Why it matters |
|---|---|---|
| Start with book income | Confirm the financial accounting starting point. | Reconciliation errors often begin with the wrong base. |
| Label each difference | Permanent, temporary, limitation, carryforward, or special schedule item. | The label determines whether the item reverses. |
| Determine direction | Add back to book income, subtract from book income, or disclose separately. | Direction errors reverse the tax result. |
| Track future effect | Deferred tax timing, carryforward use, or later reversal. | Temporary differences are not finished in the current year. |
| Review reporting form | M-1, M-3, schedule, or supporting workpaper. | Presentation must match the size and type of entity reconciliation. |
| Item pattern | Typical difference type | Direction from book income |
|---|---|---|
| Tax-exempt interest included nowhere in taxable income | Permanent difference. | Subtract if included in book income. |
| Nondeductible fines or penalties included in book expense | Permanent difference. | Add back to book income. |
| Tax depreciation exceeds book depreciation | Temporary difference. | Subtract from book income in the current year, with later reversal. |
| Book warranty expense exceeds current tax deduction | Temporary difference. | Add back until deductible for tax. |
| Charitable contribution limited for tax | Limitation or carryforward item. | Add back disallowed current amount and track carryforward. |
| NOL deduction allowed for tax but not book | Tax-only deduction or carryforward use. | Subtract when allowed in taxable income. |