Is my free zone company really exempt from UAE corporate tax?

Not automatically — the free zone benefit is conditional, and the sales pitch you heard skipped the conditions. The 0% corporate tax rate applies only to a qualifying free zone person, a status that depends on meeting all of several requirements: earning qualifying income from qualifying activities, maintaining adequate substance in the free zone, keeping non-qualifying revenue within a small de minimis limit, preparing audited financial statements, and complying with transfer pricing rules. Income from mainland customers is generally not qualifying income, which is exactly where your mixed business model becomes the live question. The sharp edge is the de minimis rule: if your non-qualifying revenue exceeds the permitted limit, you do not just pay tax on the mainland portion — you can lose qualifying status entirely, putting your income at the standard rate above the threshold. Either way, registration with the Federal Tax Authority and annual filing are required; the regime affects your rate, not your obligations. Given your free zone and mainland mix, the honest answer is that your position needs to be calculated, not assumed. A UAE tax adviser can run the qualifying-person analysis on your actual revenue split.