The short answer
HMRC does not have one general customer email address for every tax matter. Use the channel published for the issue: HMRC currently provides RD.IncentivesReliefs@hmrc.gov.uk for appropriate R&D tax relief queries, while general Corporation Tax has separate online, telephone and postal routes. If HMRC has opened an enquiry, follow the letter and case reference. An authorised specialist can deal with HMRC on the company's behalf.
What is the best way to contact HMRC?
Use the contact route published for the tax and issue you are dealing with. HMRC does not publish one general customer email address for every tax matter. For an R&D tax relief query outside Large Business, HMRC currently publishes RD.IncentivesReliefs@hmrc.gov.uk. For a general Corporation Tax matter, use HMRC’s Corporation Tax online, telephone or postal channels. If HMRC has already written to you, follow the contact instructions on that letter and quote its case reference.
Email is not automatically the best route. HMRC warns that ordinary external email can carry confidentiality, identity and interception risks. Only use an address published on GOV.UK for the issue, check it before sending, and avoid sending unnecessary personal or commercially sensitive information.
Want InnoFund to deal with HMRC on your behalf?
We can help with R&D tax relief correspondence, information requests, compliance checks, enquiries and disputes. The first step is to understand the letter or issue, identify any deadline and agree the authority HMRC needs.
HMRC contact details for common business tax issues
| Your issue | Best starting point | What to know |
|---|---|---|
| R&D tax relief technical or general query | RD.IncentivesReliefs@hmrc.gov.uk | Use the subject convention HMRC requests. Large Business customers should normally contact their Customer Compliance Manager. |
| Existing R&D enquiry or compliance check | The named officer and address or channel on HMRC’s letter | Quote the case reference, respond to the questions actually asked and protect every stated deadline. |
| General Corporation Tax query | Corporation Tax general enquiries, or 0300 200 3410 | Have the company’s 10-digit Unique Taxpayer Reference available. Current opening hours and overseas numbers are maintained on GOV.UK. |
| Corporation Tax post | Corporation Tax Services, HM Revenue and Customs, BX9 1AX, United Kingdom | Use the address on an existing Corporation Tax letter when replying to it. Include the UTR on the first page of documents. |
| R&D claim processing time | HMRC’s reply-time checker | Check the current published processing position before chasing. Sending duplicate claims or amendments can delay handling. |
| Incorrect or excessive R&D claim | R&D Disclosure Service guidance | The route depends on the error, return status and amount payable. Do not treat an ordinary email as a substitute for the prescribed disclosure process. |
| HMRC online-service problem | HMRC Online Services Helpdesk | Use this for technical access or filing-service problems rather than a question about whether expenditure qualifies. |
| Suspected HMRC scam | Report suspicious HMRC contact | Do not use contact information in the suspicious message to verify it. Check the details independently on GOV.UK. |
Contact details and opening hours can change. Follow the linked GOV.UK page rather than relying on a phone number copied into an old email, bookmark or search snippet.
Does HMRC have an email address for R&D tax credits?
Yes. HMRC’s R&D Compliance contact guidance currently publishes RD.IncentivesReliefs@hmrc.gov.uk for R&D technical and general queries outside Large Business. HMRC asks correspondents to use subject headings that identify the purpose:
- TECHNICAL QUERY for help with applying the R&D rules;
- AMENDMENT when sending an amendment, together with the required return and computation material;
- BACS, LETTER OF AUTHORITY or R&D REPORT when supplying the corresponding supporting information.
A published mailbox is not permission to send an incomplete claim, bypass an online form or ignore a live case officer. New R&D claims require the prescribed Additional Information Form before the claim is made in the Company Tax Return. An agent submitting that form must use an Agent Services Account and have the company’s permission.
What information should you have ready?
Before contacting HMRC
- The company’s legal name, company registration number and 10-digit Corporation Tax UTR.
- The accounting period and Company Tax Return or claim concerned.
- The HMRC case, letter or payment reference and the date of the correspondence.
- The name of the HMRC officer or team already dealing with the issue.
- A concise explanation of the question and the outcome being requested.
- The relevant computation, Additional Information Form and technical project evidence.
- Any response, amendment, appeal or payment deadline.
- Confirmation that the adviser has the right authority to discuss the matter.
Do not put every identifier into the subject line of an unencrypted email. Follow HMRC’s instructions for the channel and agree a suitable way to exchange sensitive or high-volume evidence.
What should you do when HMRC opens an R&D enquiry?
An R&D enquiry is a Corporation Tax compliance check. HMRC may ask about the advance sought, the scientific or technological uncertainties, the competent professionals, project boundaries and the basis for qualifying costs. The opening letter should identify what HMRC wants and when it expects a response.
- 01
Record the deadline and scope
Keep the complete letter and attachments. Identify the accounting period, projects, costs and specific questions within the check.
- 02
Preserve the evidence
Gather claim versions, computations, project records and correspondence. Do not retrospectively create a narrative that conflicts with the contemporaneous evidence.
- 03
Choose the right technical team
Coordinate the company’s competent professionals, finance team, existing accountant and any specialist adviser so that one consistent response is sent.
- 04
Confirm authority
HMRC needs valid authority before discussing confidential details with a new adviser. The appropriate route depends on whether the adviser is handling Corporation Tax generally or only the compliance check.
- 05
Answer the questions with evidence
Address HMRC’s points directly, distinguish fact from interpretation and reconcile technical explanations to the submitted figures.
How do you appoint InnoFund to contact HMRC?
You must authorise a paid tax agent before HMRC can deal with them about confidential tax affairs. For Corporation Tax, HMRC currently lists Online Agent Authorisation or paper form 64-8. If a specialist is being appointed only for a live compliance check, form COMP1 can provide temporary authority for that check without replacing the adviser who handles day-to-day tax matters.
Ongoing Corporation Tax authority
- Online Agent Authorisation or form 64-8.
- Appropriate where the agent will handle the relevant Corporation Tax affairs more broadly.
- The client must complete HMRC’s approval step.
Authority for one compliance check
- Form COMP1 identifies the periods and check covered.
- It can appoint a specialist while another adviser remains in place for ordinary matters.
- Send it to the HMRC officer dealing with the check.
Step one: book a first consultation
Send us the HMRC letter or explain the issue during a confidential first conversation. We will identify the immediate deadline, confirm whether the matter fits our R&D, innovation tax or dispute expertise, and explain the authorisation needed before we contact HMRC.
Authorisation lets HMRC exchange relevant information with the agent; it does not transfer the company’s legal responsibility for accurate returns, claims, payments or deadlines.
Can InnoFund act in an R&D dispute?
InnoFund can support the company through R&D correspondence and enquiries by reviewing HMRC’s questions, testing the technical and financial evidence, coordinating the response and communicating with HMRC once valid authority is in place. Where a formal decision is appealable, the decision letter explains the route and deadline. For direct taxes such as Corporation Tax, the normal appeal deadline is usually 30 days from the decision letter.
A service complaint is different from an appeal. Complaints concern issues such as unreasonable delay, poor communication or handling errors. Disagreement with a tax decision, penalty or refusal of relief normally requires the appeal or review route. Where legal representation or tax litigation advice is required, the appropriate legal professionals should also be involved.
Does HMRC deal with innovation funding and grants?
HMRC deals with tax matters, including R&D tax relief, Patent Box and other Corporation Tax reliefs. Most innovation grants and funding competitions are administered by the awarding body, such as Innovate UK, UK Research and Innovation or a devolved programme—not by HMRC. HMRC may still be relevant to the tax treatment of grant income or its interaction with an R&D claim, but questions about a funding application should go to the programme named in the competition guidance.
If your issue concerns an enquiry or disputed innovation-tax claim, see how our HMRC dispute resolution team can help.
Frequently asked questions
What is HMRC’s email address?
There is no single general email address for every HMRC customer query. Use the GOV.UK contact page for the relevant tax. For appropriate R&D tax relief queries, HMRC currently publishes RD.IncentivesReliefs@hmrc.gov.uk.
What is the HMRC Corporation Tax phone number?
At 5 September 2026, HMRC’s Corporation Tax general enquiries number is 0300 200 3410. Check the live GOV.UK contact page before calling because numbers and opening hours can change. Have the company’s 10-digit UTR ready.
Should I email HMRC or reply to the letter?
If the letter gives a named officer, address, email or response method, use those instructions and quote the case reference. A general mailbox may not reach the team managing the case and does not stop a deadline.
Can InnoFund contact HMRC for my company?
Yes, for matters within our R&D, innovation tax and dispute expertise, once the scope is agreed and HMRC has the appropriate agent or compliance-check authority.
Can my accountant remain appointed?
Potentially. HMRC’s COMP1 process can appoint a specialist for a particular compliance check while the existing agent continues with day-to-day tax work. The right arrangement depends on the authorities already held and the scope of HMRC’s check.
How long does HMRC take to reply?
Times depend on the issue and current workload. HMRC maintains an online checker for several Corporation Tax requests and updates it weekly. Check that service before sending a duplicate request.
Can a complaint overturn an R&D decision?
A complaint deals with service or handling. To challenge a tax decision, penalty or refusal of relief, follow the appeal or review instructions and deadline in HMRC’s decision letter.
How can I check whether an HMRC message is genuine?
Do not use a phone number or link in a suspicious message to verify it. Find the relevant contact details independently on GOV.UK and use HMRC’s suspicious-contact reporting service where appropriate.
Check the detail
Sources & scope
United Kingdom. Contact routes, telephone opening hours and authorisation methods checked on 5 September 2026. Always verify current details on the linked GOV.UK page and follow any case-specific instructions or deadline in HMRC correspondence.
This is an InnoFund explanation, not official guidance or advice on a particular claim. The facts, relevant law and applicable scheme rules must be considered together.
Sources checked: 5 September 2026. This is separate from expert sign-off.
- HMRC Corporate Intangibles R&D Manual: R&D Compliance contact details
CIRD80350; published R&D mailbox, subject conventions, post and status queries
- HMRC: Corporation Tax general enquiries
Current online, telephone and postal contact routes
- HMRC: Authorising an agent to deal with your tax affairs
Client authorisation, form 64-8 and compliance-check authority
- HMRC: Ways tax agents can obtain client authorisation
Corporation Tax authorisation methods and limits
- HMRC: Online Agent Authorisation
Request, posted code and client approval process
- HMRC: Temporary compliance-check authorisation
COMP1 scope and written consent
- HMRC: Tax compliance checks
What HMRC may check and adviser involvement
- HMRC: Disagree with a tax decision
Direct-tax appeal information and usual 30-day deadline
- HMRC: Check when to expect a reply
Corporation Tax response-time checker
- HMRC: R&D Additional Information Form
Required claim information and agent submission
- HMRC: R&D Disclosure Service
Correcting excessive claims and published R&D contact route
- HMRC: Complain about HMRC
Difference between a service complaint and an appeal
- HMRC operational guidance: external email risks
Confidentiality, identity and interception considerations
- HMRC: Online Services Helpdesk
Technical access and filing-service problems
- HMRC: Report suspicious contact
Verifying and reporting possible HMRC scams