How does an unrealized gain on AFS debt securities create a deferred tax liability, and where is it recognized?

Excellent observation — this is a nuanced area that connects OCI accounting with deferred taxes. When an AFS debt security has an unrealized gain, the book value exceeds the tax basis, creating a taxable temporary difference and a deferred tax liability (DTL).

The Mechanics:

1. AFS debt security increases in fair value → unrealized gain recognized in OCI (pre-tax)
2. The tax basis remains at original cost (no tax event has occurred)
3. Book basis > Tax basis → DTL
4. The DTL is also recognized in OCI (matching the related item)

Why Does the Tax Effect Go to OCI?

The principle is that the deferred tax follows the underlying item. Since the unrealized gain bypasses the income statement and goes to OCI, the related tax effect also goes to OCI. This prevents distortion of reported tax expense on the income statement.

Worked Example — Ashworth Financial:

Ashworth purchases AFS bonds for $5,000,000. At year-end, fair value = $5,400,000. Tax rate = 25%.

Unrealized gain: $5,400,000 − $5,000,000 = $400,000

Deferred tax liability: $400,000 × 25% = $100,000

Journal Entry:

Net OCI impact: $400,000 − $100,000 = $300,000 (after-tax OCI)

On the Balance Sheet:

When the Security is Sold:

Upon sale, both the unrealized gain and the DTL are "unwound":

• The realized gain goes to P&L (reclassification adjustment)
• The DTL is reversed against current tax payable
• AOCI returns to zero for this security

Year 2 — Ashworth sells the bonds for $5,400,000:

*Actual tax on the realized gain.

Key Exam Points:

1. Deferred tax on OCI items is also recognized in OCI, not in income tax expense.
2. An unrealized gain → DTL (book > tax basis); an unrealized loss → DTA.
3. When sold, both the gain and the deferred tax are reclassified to P&L.
4. The net after-tax OCI = Pre-tax OCI × (1 − tax rate).
5. This same logic applies to all OCI items (pension adjustments, hedges, translation).

Practice deferred tax and OCI in our CFA Level II question bank.