A deferred tax asset becomes cash when the timing difference reverses. The reserve becomes a write-off, the loss carryforward reaches a profitable year, and the credit offsets a real liability. In that year, taxable income drops, the check to the IRS shrinks, and the asset leaves the balance sheet.

The reversal has rules. The 80% income limit on post-2017 losses means a large carryforward is used in slices, and a company can owe some tax even while sitting on losses. For example, a company carrying a $1 million net operating loss into a year with $500,000 of taxable income can offset only $400,000 of it, so $100,000 is still taxed despite the loss. We model which year absorbs each slice as part of your business tax work, because timing a deduction into a high-rate year saves real money.

A valuation allowance reduces a deferred tax asset when it is more likely than not that part of it will never be used. Accounting standards (ASC 740) put the burden of proof on you: a history of losses is the classic strike against realizability, and it is the first thing a reviewer or auditor will probe.

Writing an allowance up or down swings reported earnings without a dollar changing hands, which is why lenders and investors read this line closely. If your statements go through a review or an audit, the support for this judgment call needs to exist before anyone asks for it.