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Tax Optimiser
Terms of Service
Last updated: 21 May 2026
These Terms of Service set out the basis on which you may access and use the Tax Optimiser software and services. Please read them carefully and save a copy for your records.
1. Introduction and these terms
- 1.1
These Terms of Service (the “Terms”) govern your access to and use of the Tax Optimiser website at www.taxoptimiser.co.uk and the related online software, tools and services we provide (together, the “Service”).
- 1.2
The Service is operated by Tax Optimiser Ltd, a company registered in England and Wales under company number 11137513, whose registered office is at 86-90 Paul Street, London, England, EC2A 4NE (“Tax Optimiser”, “we”, “us” or “our”). Our data protection registration number with the Information Commissioner’s Office is ZA473706.
- 1.3
By creating an account, subscribing to, accessing or using the Service, you confirm that you accept these Terms and that you agree to comply with them. If you do not agree to these Terms, you must not use the Service.
- 1.4
In these Terms, “you” and “your” mean the person or organisation using the Service. If you use the Service on behalf of a business, firm or other organisation, you confirm that you have authority to bind that organisation to these Terms, and “you” includes that organisation.
- 1.5
These Terms should be read together with our Privacy Policy, which explains how we collect and use personal data. Where there is any conflict between these Terms and a separate written agreement signed by us, that signed agreement will prevail.
- 1.6
We recommend that you save or print a copy of these Terms for your records.
2. Definitions
- 2.1
In these Terms, the following words have the following meanings:
- “Account” – the account you register in order to access the Service.
- “Customer Data” – all data, financial records, spreadsheets, trial balances, figures, documents and other information that you, your users or your integrations upload to, enter into, or generate within the Service, including data relating to organisations or clients for whom you act.
- “Organisation” – a business, company or other entity for which returns, accounts or submissions are prepared or filed through the Service.
- “Submission” – any VAT return, MTD ITSA update or submission, Corporation Tax return (CT600), set of statutory or other accounts, or other filing transmitted through the Service to HMRC, Companies House or any other authority.
- “Subscription” – a paid or free plan giving you access to the Service for a defined period.
- “Fees” – the charges payable for a Subscription or for use of the Service, as set out on our pricing page or otherwise notified to you.
- “HMRC” – His Majesty’s Revenue and Customs.
3. The Service
- 3.1
The Service is cloud-based software that helps accountants and businesses prepare and submit tax and accounting information, including Making Tax Digital (MTD) VAT returns, MTD for Income Tax Self Assessment (ITSA), Corporation Tax returns (CT600), accounts production and working papers, and to file Submissions with HMRC and Companies House.
- 3.2
The Service is recognised by HMRC and Companies House for the relevant submission types. Recognition relates to the technical compatibility of our software with their systems. It does not mean that HMRC, Companies House or any other authority endorses, checks or guarantees the content, accuracy or completeness of any Submission you make.
- 3.3
Some features (for example, MTD for ITSA) may be described as forthcoming, in development, or in beta. We give no commitment that any particular feature will be released, or released by any particular date, and any forward-looking statement about the Service is not a contractual promise.
- 3.4
We may add, change, suspend or remove features of the Service from time to time in order to improve it, to reflect changes in law or the requirements of HMRC or Companies House, or for technical or commercial reasons. We will try to give reasonable notice of material changes that adversely affect you.
4. Eligibility and your account
- 4.1
To use the Service you must be at least 18 years old and capable of entering into a legally binding contract. The Service is intended for business use and not for consumers acting outside their trade, business, craft or profession.
- 4.2
You must provide accurate, current and complete information when registering an Account and keep that information up to date.
- 4.3
You are responsible for keeping your login credentials confidential and for all activity that takes place under your Account. You must notify us promptly at hello@taxoptimiser.co.uk if you believe your Account has been accessed without authorisation.
- 4.4
Where you create users or sub-accounts (for example, members of your firm or staff), you are responsible for their use of the Service and for ensuring they comply with these Terms.
- 4.5
If you act as an accountant, tax agent or adviser for an Organisation, you confirm that you hold the necessary authorisations, agent codes and client permissions to act for that Organisation and to make Submissions on its behalf.
5. Subscriptions, fees and payment
- 5.1
Access to the Service may be offered on free and paid Subscriptions. Current Fees, plan features and any free-of-charge allowances (for example, free use for an individual organisation for an initial period) are set out on our pricing page and may change from time to time.
- 5.2
Payments and recurring Subscription billing are processed on our behalf by Stripe, Inc. and its affiliates (“Stripe”). By providing payment details you authorise us and Stripe to charge the applicable Fees to your chosen payment method. Your use of Stripe is subject to Stripe’s own terms and privacy policy.
- 5.3
Unless stated otherwise, paid Subscriptions renew automatically at the end of each billing period (for example, monthly or annually) at the then-current Fees, until cancelled in accordance with clause 6. Where a free period is offered, the Subscription will, unless cancelled, convert to a paid Subscription at the end of that free period.
- 5.4
We may change our Fees. For existing Subscriptions, any change will take effect from your next renewal, and we will give you reasonable advance notice so that you can cancel before the change takes effect if you do not wish to continue.
- 5.5
Fees are stated exclusive of VAT and any other applicable taxes, which will be added where they apply.
- 5.6
If a payment fails or is overdue, we may retry the payment, suspend your access to the Service, or restrict your ability to make Submissions until payment is received. Suspension for non-payment does not relieve you of your obligation to pay outstanding Fees.
6. Cancellation and refunds
- 6.1
You may cancel your Subscription at any time through your Account settings or by contacting us at hello@taxoptimiser.co.uk.
- 6.2
When you cancel, your Subscription and access to the relevant paid features will continue until the end of the billing period for which you have already paid, and will not renew after that. Cancellation does not interrupt the current billing period.
- 6.3
Except where required by law, Fees are non-refundable. We do not provide refunds or credits for partial billing periods, for periods during which the Service was not used, or for Subscriptions cancelled part-way through a billing period.
- 6.4
Nothing in this clause 6 affects any statutory rights that apply to you and that cannot lawfully be excluded or limited.
7. Your responsibilities – data accuracy and deadlines
- 7.1
The Service is a tool that transmits information you prepare. It does not prepare your accounts or tax position for you, and it does not verify that your figures are correct. You are responsible for the Customer Data and for every Submission made through your Account.
- 7.2
In particular, you are solely responsible for:
- ensuring that all Customer Data entered into, imported into, or used within the Service is accurate, complete, current and free from error;
- reviewing, checking and approving every return, set of accounts and other Submission, in full, before it is filed;
- ensuring that every Submission to HMRC, Companies House or any other authority is made on time and by the applicable statutory or regulatory deadline;
- confirming, after submitting, that each Submission has actually been received and accepted by the relevant authority, and taking corrective action if it has not;
- holding and maintaining any registrations, authorisations, agent codes and client permissions required to make Submissions; and
- keeping your own copies and records of Customer Data and Submissions as required by law.
- 7.3
Deadlines are your responsibility. We do not monitor your filing deadlines and we give no assurance that a Submission will be processed before any deadline. You should allow ample time before any deadline to prepare, review, submit and confirm acceptance of each Submission.
- 7.4
We are not responsible or liable for any penalty, interest, surcharge, fine, assessment, additional tax, loss or other consequence arising from inaccurate, incomplete or late Customer Data, from a Submission that is incorrect, rejected, delayed or not made, or from your failure to meet a deadline.
8. AI-assisted categorisation
- 8.1
Certain features of the Service use a third-party artificial intelligence provider to suggest categorisations of nominal accounts and trial balance data – for example, when populating Corporation Tax returns or statutory accounts from data imported from Xero, QuickBooks or a spreadsheet.
- 8.2
AI-generated categorisations are provided as a convenience and a starting point only. They are automated suggestions. They may be incomplete, inaccurate, mis-categorised or unsuitable for the Organisation’s circumstances, and they may not reflect current law, accounting standards or HMRC or Companies House requirements.
- 8.3
Before any AI-assisted categorisation feature is used, the Service displays a warning to this effect. By proceeding past that warning and using the feature, you acknowledge and accept the limitations described in this clause 8.
- 8.4
It is your responsibility – and, where you act for an Organisation, the responsibility of the accountant, agent or adviser acting for that Organisation – to review, verify, correct and approve every AI-generated categorisation, and all underlying Customer Data, before it is relied upon or included in any Submission.
- 8.5
We do not check, audit, validate or guarantee the accuracy, completeness or suitability of any AI-generated categorisation or of any Customer Data. We are not liable for any loss, penalty or other consequence arising from reliance on an AI-generated categorisation, and using the AI feature does not transfer responsibility for the accuracy of your data to us.
- 8.6
Customer Data processed through AI features may be transmitted to and processed by our third-party AI provider for the purpose of generating categorisation suggestions. Such processing is carried out subject to our Privacy Policy and applicable data protection law.
9. Submissions to HMRC and Companies House
- 9.1
Where you instruct the Service to make a Submission, the Service transmits the Customer Data you have prepared, reviewed and approved to HMRC, Companies House or another authority. In doing so we act only as a conduit for that data.
- 9.2
We do not control, and are not responsible for, the systems, availability, processing times, decisions, validation rules or responses of HMRC, Companies House or any other authority, nor for whether they accept, reject, query or process any Submission.
- 9.3
Transmission of a Submission through the Service is not confirmation that it has been accepted. A Submission may be rejected or queried by the receiving authority. You are responsible for monitoring the status of each Submission and for resubmitting or correcting it where necessary.
- 9.4
Your dealings with HMRC and Companies House remain governed by their own rules, requirements and terms. Nothing in the Service changes your legal obligations to those authorities.
10. Third-party integrations and services
- 10.1
The Service integrates with, and relies on, third-party products and services, which may include accounting platforms such as Xero and QuickBooks, the payment processor Stripe, the email delivery provider Postmark, the analytics provider Google Analytics, and a third-party AI provider used for categorisation.
- 10.2
Where you connect a third-party account (for example, Xero or QuickBooks) to the Service, you authorise the Service to access, import and exchange data with that account as needed to provide the features you use. Your use of those third-party products remains subject to the third party’s own terms and policies.
- 10.3
We are not responsible for third-party products and services, for their availability or accuracy, or for any act or omission of a third-party provider. If a third-party service changes, is interrupted or is withdrawn, the relevant features of the Service may be affected.
11. Data protection and privacy
- 11.1
We process personal data in accordance with our Privacy Policy and with applicable data protection law, including the UK GDPR and the Data Protection Act 2018.
- 11.2
Where the Service processes personal data contained in Customer Data on your behalf (for example, personal data relating to an Organisation or its clients), you act as the data controller and we act as a data processor. We will process that personal data only on your documented instructions, as set out in these Terms, our Privacy Policy and any applicable data processing terms, and as needed to provide the Service.
- 11.3
You are responsible for ensuring that you have a lawful basis to provide Customer Data to us and to have it processed through the Service, including where it is processed by our sub-processors such as Stripe, Postmark, Google Analytics and our AI provider.
- 11.4
We implement appropriate technical and organisational measures designed to protect Customer Data. However, no method of transmission or storage is completely secure, and you remain responsible for keeping your own backups and records.
12. Acceptable use
- 12.1
You must not, and must not permit anyone else to:
- use the Service for any unlawful, fraudulent or fraudulently inaccurate purpose, including submitting information you know or suspect to be false;
- use the Service to make a Submission for an Organisation you are not authorised to act for;
- upload or transmit any material that contains viruses or other harmful code, or that infringes the rights of any third party;
- attempt to gain unauthorised access to the Service, its systems or other users’ data, or interfere with or disrupt the Service;
- copy, modify, reverse-engineer, decompile or create derivative works from the Service, except to the extent permitted by law;
- resell, sublicense or otherwise commercially exploit the Service except as expressly permitted by us; or
- use the Service in a way that could damage, disable, overburden or impair it.
- 12.2
We may investigate suspected breaches of this clause 12 and may report unlawful activity to the relevant authorities.
13. Intellectual property
- 13.1
The Service, including its software, design, text, graphics and trade marks, and all intellectual property rights in it, belong to Tax Optimiser or our licensors. Nothing in these Terms transfers any of those rights to you.
- 13.2
Subject to your compliance with these Terms and payment of applicable Fees, we grant you a non-exclusive, non-transferable, revocable licence to access and use the Service for your own business purposes during your Subscription.
- 13.3
You retain all rights in your Customer Data. You grant us a non-exclusive licence to host, copy, transmit, process and display Customer Data as necessary to provide and maintain the Service, to make Submissions on your instruction, and to comply with our legal obligations.
- 13.4
We may use aggregated and anonymised data derived from use of the Service (which does not identify you or any individual) to operate, analyse and improve the Service.
- 13.5
If you give us feedback or suggestions about the Service, we may use them without restriction and without any obligation to you.
14. Availability, support and maintenance
- 14.1
We aim to make the Service available reliably, but we do not guarantee that it will be uninterrupted, error-free or available at any particular time. Access may be affected by maintenance, updates, technical issues, or matters outside our control, including the availability of HMRC, Companies House or third-party services.
- 14.2
We may carry out planned or emergency maintenance. We will try to schedule planned maintenance to minimise disruption and to give notice where reasonably practicable.
- 14.3
We provide customer support by email at hello@taxoptimiser.co.uk and by telephone. Our support hours are Monday to Friday, 9:00am to 5:00pm UK time, excluding public holidays in England and Wales. We aim to respond to support requests within a reasonable time, but we do not guarantee a specific response or resolution time. Given these support hours, you should not rely on receiving support outside them, including immediately before a filing deadline.
15. Suspension and termination
- 15.1
We may suspend or restrict your access to all or part of the Service, or terminate these Terms and your Account, if: (a) you materially breach these Terms and, where the breach can be remedied, fail to remedy it within a reasonable period after we ask you to; (b) Fees are overdue; (c) we reasonably believe the Service is being used unlawfully or fraudulently, or in a way that risks harm to us, other users or any third party; or (d) we are required to do so by law or by HMRC, Companies House or another authority.
- 15.2
We may also stop providing the Service, or a part of it, by giving you reasonable notice.
- 15.3
You may terminate these Terms at any time by cancelling your Subscription and ceasing to use the Service, subject to clause 6.
- 15.4
On termination: (a) your right to access and use the Service ends; (b) any Fees already due remain payable; and (c) clauses that by their nature should survive (including clauses 7, 8, 13, 16, 17, 18 and 21) continue to apply.
- 15.5
You are responsible for exporting or retaining your own copies of Customer Data before termination. After termination we may delete Customer Data in accordance with our Privacy Policy and our data retention practices, subject to any legal obligation to retain it. You should not rely on us as a system of record.
16. Disclaimers – no professional advice
- 16.1
Tax Optimiser provides software. We are not your accountant, tax adviser, auditor or legal adviser, and the Service does not provide accountancy, tax, audit, legal or financial advice. Nothing produced by or within the Service constitutes professional advice or a substitute for it. You are responsible for obtaining your own independent professional advice where appropriate.
- 16.2
We do not check, verify or guarantee the accuracy, completeness or compliance of any Customer Data, calculation, categorisation, set of accounts, return or Submission. Responsibility for the correctness of all such information rests with you and, where relevant, with the accountant or agent acting for the Organisation.
- 16.3
To the fullest extent permitted by law, the Service is provided on an “as is” and “as available” basis, and we exclude all warranties, conditions and terms implied by statute, common law or otherwise, including any implied terms as to satisfactory quality, fitness for a particular purpose and accuracy.
17. Limitation of liability
- 17.1
Nothing in these Terms limits or excludes our liability for: (a) death or personal injury caused by our negligence; (b) fraud or fraudulent misrepresentation; or (c) any other liability that cannot lawfully be limited or excluded.
- 17.2
Subject to clause 17.1, we will not be liable to you, whether in contract, tort (including negligence), breach of statutory duty or otherwise, for any:
- penalty, interest, surcharge, fine, assessment or additional tax imposed by HMRC, Companies House or any other authority;
- loss or consequence arising from inaccurate, incomplete or late Customer Data, or from a Submission that is incorrect, rejected, delayed or not made;
- loss of profit, revenue, business, contracts, anticipated savings or goodwill;
- loss or corruption of data, except to the extent directly caused by our breach of these Terms; or
- indirect or consequential loss.
- 17.3
Subject to clause 17.1, our total aggregate liability to you arising out of or in connection with these Terms and the Service, whether in contract, tort (including negligence), breach of statutory duty or otherwise, will not exceed the total Fees paid by you to us for the Service in the twelve (12) months immediately before the event giving rise to the claim. Where you have used the Service free of charge, no Fees will have been paid and our total aggregate liability to you under this clause will accordingly be zero.
- 17.4
Each provision of this clause 17 operates separately. If any part is held to be unenforceable, the remaining parts continue to apply.
- 17.5
You are responsible for arranging appropriate insurance (for example, professional indemnity insurance) for your business and your use of the Service. The allocation of risk in these Terms is reflected in our Fees.
18. Indemnity
- 18.1
You agree to indemnify and hold us harmless against all losses, liabilities, costs, claims, damages and expenses (including reasonable legal fees) arising out of or in connection with: (a) your breach of these Terms; (b) Customer Data, including any claim that it is inaccurate, unlawful or infringes the rights of a third party; (c) any Submission made through your Account; or (d) your use of the Service in breach of applicable law or the rights of any third party.
19. Confidentiality
- 19.1
Each party may receive confidential information from the other in connection with the Service. Each party will keep the other’s confidential information confidential and use it only as needed in connection with these Terms, except where disclosure is required by law or by a regulatory authority. This clause does not apply to information that is or becomes publicly available other than through a breach of these Terms.
20. Changes to these Terms
- 20.1
We may update these Terms from time to time, for example to reflect changes in the Service, in law, or in the requirements of HMRC or Companies House. The current version will always be available on our website, with the “Last updated” date shown at the top.
- 20.2
We will give reasonable notice of material changes, for example by email or by notice within the Service. Your continued use of the Service after a change takes effect constitutes acceptance of the updated Terms. If you do not agree to a change, you should stop using the Service and may cancel in accordance with clause 6.
21. General
- 21.1
Force majeure. We are not liable for any failure or delay in performing our obligations caused by events beyond our reasonable control, including failures of internet, hosting or third-party services, acts of government or regulatory authorities, or outages affecting HMRC or Companies House.
- 21.2
Assignment. You may not assign or transfer your rights or obligations under these Terms without our written consent. We may assign or transfer these Terms in connection with a reorganisation, merger or sale of our business.
- 21.3
Entire agreement. These Terms, together with our Privacy Policy and any document expressly referred to in them, constitute the entire agreement between you and us in relation to the Service and supersede any prior arrangements.
- 21.4
Severability. If any provision of these Terms is found to be invalid or unenforceable, the remaining provisions continue in full force and effect.
- 21.5
Waiver. A failure or delay by us in exercising any right under these Terms does not waive that right.
- 21.6
No partnership. Nothing in these Terms creates a partnership, agency or employment relationship between you and us.
- 21.7
Third parties. A person who is not a party to these Terms has no rights under the Contracts (Rights of Third Parties) Act 1999 to enforce any of its terms.
- 21.8
Notices. Notices to us should be sent to hello@taxoptimiser.co.uk. We may give notices to you by email to the address on your Account or by notice within the Service.
22. Governing law and jurisdiction
- 22.1
These Terms, their subject matter and their formation are governed by the law of England and Wales.
- 22.2
The courts of England and Wales have exclusive jurisdiction to settle any dispute or claim arising out of or in connection with these Terms or the Service, except that we may bring proceedings to recover unpaid Fees in any competent court.
23. How to contact us
Tax Optimiser Ltd
Company number: 11137513 (registered in England and Wales)
Registered office: 86-90 Paul Street, London, England, EC2A 4NE
ICO data protection registration: ZA473706
Email: hello@taxoptimiser.co.uk
Telephone: 07879 77 58 40 (Monday to Friday, 9:00am–5:00pm UK time)
Website: www.taxoptimiser.co.uk