UK Tax Calculators - Wordpress website

General information for the website:
1. Landing page - Template available
2. What we do Page
3. Calculator Plugin Page

KEY TASK IS PLUGIN FOR CALCULATORS (Inc Calculators)
Description of every page/module: Looking for a stand-alone script/ plugin for calculators to be integrated into accountant websites.

Must be customizable and allow for easy backend updates of calculation percentages etc.

Must work like this and layout also be similar to the examples below:

http://www.easyaccountancy.co.uk/calculators-0
http://www.jonesandpartners.co.uk/calculators
https://www.parkercavendish.co.uk/resources/online-calculators

No Formula Will be Provided. have to calculate from the examples.

Calculators:
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Income tax Calculator
CIS tax deduction calculator
Self Employed Tax Calculator
Capital Gains Tax
Company car and fuel benefit-in-kind
Loan calculator
Mortgage calculator

Proposal
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You should be very specific and must be able to fulfil all the requirements.
- Submit detailed Proposal
- Establish your understanding of the project by demonstrating what and how you going to achieve these.
- Clear pricing and ETA
- Description of requirements/features: Requirements

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1. Stand Alone wordpress plugin
2. Settings Must allow to change percentage or other variable if needed in future.
3. Settings Must allow to change colour / layout to match whole website
4. You must figure out all calculation algorithm from above examples / knowledge
5. We should have sole rights on this project.
6. surrender source code and sign NDA
7. Must Provide documentations