Every calculator on HisaabHub follows the same process. This page explains it, so you can judge how far to rely on a result.
1. We start from the primary source
Each calculator is built from the law or official guidance that sets the rule:
- UAE e-invoicing: Ministerial Decision No. 243 of 2025 (as amended) and Cabinet Resolution No. 106 of 2025 on fines.
- UAE VAT: Federal Decree-Law No. 8 of 2017 on VAT, its Executive Regulation, and Federal Tax Authority guidance, including the penalty changes in Cabinet Decision No. 129 of 2025.
- UAE corporate tax: Federal Decree-Law No. 47 of 2022, related Cabinet and Ministerial Decisions, and Ministry of Finance announcements such as the extension of Small Business Relief.
- UAE gratuity: Article 51 of Federal Decree-Law No. 33 of 2021 on the regulation of labour relations.
- Saudi VAT and e-invoicing: ZATCA’s VAT law, implementing regulations and e-invoicing rules.
- Saudi end-of-service: Articles 84, 85, 87 and 88 of the Saudi Labor Law, as amended in 2025.
- Zakat: the 2.5% rate and the nisab weights of 85 g of gold and 595 g of silver, which are widely agreed. Where scholars differ, we say so and let you choose.
Secondary sources, such as news reports and adviser articles, are used only to find out that something changed. We then confirm it against the official source before changing a calculator.
2. We show our working
Results list each step: the bands, rates and amounts that produced the answer. If a result surprises you, you can see exactly where it came from.
3. We state the assumptions
Each calculator has a note under the result listing what it does not cover. For example, the corporate tax calculator does not include tax groups, transfer pricing or losses brought forward, and the gratuity calculator applies to private-sector employees on the UAE mainland, not the DIFC or ADGM.
4. We date everything
Each calculator shows the date its rules were last checked, and each page shows when it was last updated. When a rate, threshold or deadline changes, we update the calculator, re-check the worked examples on the page, and update related guides.
5. Your data stays with you
The calculations run in your browser. We do not store the numbers you enter or send them to our server.
What the results are, and are not
The results are careful estimates based on published rules. They are not legal, tax or financial advice, and they cannot take into account every detail of your situation. Before you file a return, sign a settlement or make a decision with money at stake, confirm with the relevant authority or a qualified adviser.
If you think a calculator is wrong, please contact us with the details.