Two lines in the Corporate Tax report handle differences of timing rather than of principle. Line 20 is Unrealized gains/losses adjustment and line 21 is Book-vs-tax depreciation timing difference. On the demo both read 0.00, because the sample company has nothing in either.

The distinction that makes them make sense: an add-back for a fine is permanent, because the deduction is gone for good. A depreciation difference is temporary — the accounts and the tax computation disagree about when an amount is recognised, and across the life of the asset the disagreement sums to zero. Treating a temporary difference as a permanent one is how a company ends up taxed twice on the same amount.

The Depreciation Bridge screen at Accounting → Configuration → UAE Tax Reports → Depreciation Bridge is where that difference is held as a record instead of being rebuilt in a spreadsheet each March. Beside it, CT Adjustments — described in the module guide as "book-to-tax add-backs, deductions and unrealized restatements used by the CT report" — carries the rest of the bridge, including the restatement that feeds line 20.

Worked example — one asset, two lives. An asset is depreciated at AED 250,000 a year in the accounts and at AED 180,000 a year on the basis you use for tax. Line 21 adds back the difference, AED 70,000, in each of those years. Because the cost being written off is the same in both, the amounts eventually reverse and the line turns negative. The test of a correct bridge is that line 21 sums to zero across the asset's whole life. If it does not, the bridge is leaking — either a permanent difference has been filed in a temporary line, or an asset was never reconciled between the two bases.

MISSING FACT: the CT Law provisions governing the realisation basis election for unrealized gains and losses, and the basis on which depreciation is allowed for Corporate Tax. Neither was in the verified law pack for this course, so this lesson teaches the mechanics of the two lines and leaves the rule that sets the tax figure to your advisor.

The failure mode is the spreadsheet. A bridge kept outside the system reconciles beautifully in the year it is built and cannot be reproduced two years later, when its author has left and an auditor wants the opening balance explained. Record it where the period is recorded. That is the entire argument for the screen.