A Corporate Tax rate is not a constant. It is a figure an instrument sets, on a date, until another instrument changes it. Federal Decree-Law 47/2022 Art. 3 sets two bands — 0% on taxable income up to AED 375,000, and 9% above it — and Cabinet Decision 116/2022 fixes them. The band belongs to the taxable person, not to each business that person runs. Then on 29 July 2026 Ministerial Decision 131/2026 moved the Small Business Relief sunset, and one of the four numbers behind the computation changed without the law being reissued.

That is the mental model for CT Rate Config: four parameters held together in a window with a Valid From and a Valid To. The module guide describes the screen as "dated windows holding the 0% threshold, 9% rate, Small Business Relief cap and loss-relief cap", seeded with defaults on install. The report computes a period by finding the window that covers it, so the rate applied to a period is a matter of record rather than a matter of code.

Open it at Accounting → Configuration → UAE Tax Reports → CT Rate Config. The list carries one row per window, with columns for Company, Valid From, Valid To, 0% Threshold, CT Rate (%), the Small Business Relief cap and the Tax-loss Relief cap.

What you will actually find on the demo, August 2026. CT Rate Config is empty. The screen shows its own empty state: "Define the Corporate Tax parameters for a dated window. Set the 0% threshold, the headline rate, the Small Business Relief revenue cap and the tax-loss relief cap. Windows must not overlap." The module guide says defaults are seeded on install; the public demo has none. This is a seeding gap on the demo rather than a product behaviour, but it does mean you cannot learn this screen by reading it. Use the table below instead — it is what a correct first window holds.

Look at the Valid To. Only one of those four parameters has a known end date, and it is the Small Business Relief cap. Cut the window there rather than leaving it open-ended: on 1 January 2030 you open a second window carrying the same bands and the same loss cap, with whatever the instrument governing later periods turns out to say. Two windows, adjacent, never overlapping. Do not pre-fill the second one with a guess.

Why overlap is the failure mode. If two windows both cover 1 July 2027, the computation for that day has two answers and no rule for choosing between them. The screen's own empty state spells out the constraint, so treat it as a validation you check by eye before saving: every window's Valid From is the day after the previous window's Valid To. Gaps are the same fault in the other direction — a period no window covers is a period with no rate to apply.

CT Tax Periods sits beside it in the same menu, and it is the spine of everything else in this course. The Small Business Relief election, the loss brought forward, the transfer-pricing disclosure and the DMTT test are all facts about a tax period, not about a company. Record your periods first and everything after has somewhere to attach itself. Course 2.1 showed the report already deriving the filing deadline from the period — the demo header reads FY 2026 · Filing due 2027-09-30, nine months after a 31 December 2026 year end, exactly as CT Law Art. 53(1) requires.

One honest note about the click paths in this course. The module guide documents six configuration screens: UAE Tax Settings, VAT Box Mapping, Emirate Mapping, CT Rate Config, CT Adjustments and Tax Filings. The menu on the demo carries six more — CT Tax Periods, TP Disclosures, SBR Elections, Tax-loss Register, Depreciation Bridge and Payment/Benefit Types — and those are the subject of the lessons that follow. Where the guide is silent on a field, this course tells you what the law requires the record to hold and leaves you to read the field labels off your own installation rather than inventing them here. The Corporate Tax report's toolbar also carries a CT Inputs dropdown, which is the route to these screens from the report itself.