Key terms explained for the Domestic Renewable Heat Incentive

These key terms have been designed as a reference tool when you need more detail on a specific topic.

You can also download this as a pdf: Domestic RHI reference document

Air quality

Biomass products that are first commissioned after scheme launch need to meet the RHI air quality requirements. The air quality requirements set limits on the emissions a product can produce. Products must operate within these limits to be eligible for the Domestic RHI scheme. Under the scheme, emissions of particulate matter (PM) must not exceed 30 grams per gigajoule net heat output, and emissions of oxides of nitrogen (NOx) must not exceed 150 grams per gigajoule net heat output.
‘Legacy participants’ (those whose product was commissioned before scheme launch) don't need to meet these requirements.

Products affected by these requirements will need to have an RHI Emission Certificate. To check whether a product has an RHI emission certificate, please see the Product Eligibility List in the first instance.

You will not usually receive a copy of the emission certificate for your heating system, but may be able to access a copy using the HETAS RHI Emission Certificate List. Please note that the HETAS list may not be comprehensive.

The emissions certificate contains information about the product and laboratory where the testing took place, along with information on the emissions and tested fuel types for the product. For a full list of information included on the emission certificate, see the Emission Certificate (RHI) section of this guide.

In terms of the air quality requirements, you must:

  •  use a fuel type specified on the emissions certificate,
  •  use a fuel that does not exceed the maximum moisture content specified on the certificate, and
  •  operate your heating system in accordance with the manufacturer’s instructions in relation to the control of emissions of particulate matter and oxides of nitrogen.

You will need to follow these rules for the duration of the seven year payment period in order to remain eligible to receive payments and will need to declare that you are meeting the air quality requirements on an annual basis. We may also ask you to provide evidence of compliance with these requirements, so we strongly recommend keeping any fuel receipts, records of transactions or annual statements of fuel purchased  for the entire time (seven years) you’re a member on the Domestic RHI scheme.


Annual declarations

If your application to the Domestic RHI is approved you will need to declare each year that you comply with the scheme requirements.

Please note: your installer may not fill out your annual declaration for you. This is because you are making declarations about your property and heating system, for which you are responsible; not your installer.

You will need to submit the following declarations online once a year:

  1. That you continue to own the heating system.
  2. That, to the best of your knowledge and belief, you or the previous owner did not:
    a. receive a grant from public funds that went towards the cost of purchase or installation of the heating system, other than any grant declared to Ofgem on application.
    b. receive funding from any source which completely covered the cost of purchase or installation of the heating system.
  3. That the heating system is in good working order and has not been replaced.
  4. The number of days that the property has been occupied over the past 12 months and the number of days you expect the property to be occupied over the next 12 months.
  5. That, if you do not live in the property, the occupants of the property have agreed to permit access by the Department for Business, Energy & Industrial Strategy (BEIS), Ofgem, or an authorised third party acting on behalf of BEIS or Ofgem.
  6. If you have an accredited meter; that it is in good working order.
  7. (If you have a biomass system) If you’ve been using BSL approved fuel and the BSL fuel authorisation number.

We ask you to do this every year because the scheme is funded by public money. We must ensure that you’re continuing to follow the scheme rules so that we can pay you the correct amount of money for the renewable heat your heating system produces.


Application rejection

Not all applicants who apply for the Domestic RHI will be eligible. This paragraph explains what happens if your application is rejected.

There are three points at which your application could be rejected:

  • automatic rejection when completing initial eligibility questions on the application form
  • automatic rejection when completing further application form questions
  • rejection following review by our team.

When you first register for an account, you will have to fill out some initial eligibility questions. These questions check the validity and eligibility of your certificates and cover some of the key eligibility criteria for the scheme.  If your responses to these questions determine that you are not eligible for the scheme we will inform you of the reason for rejection and you will not be able to proceed further with the application form.

If you pass these initial eligibility questions, you will be able to proceed with making an application. It is possible that you could be automatically rejected at this point; we will inform you of the reason, for example if you fail your identity check.

If we are unsure of your eligibility at this stage, or need further information in order to make a decision, we will place your application into review. Once we have completed the review, we will notify you as to whether you are eligible or not. If you are not eligible and we reject your application, we will email to explain why.

If you are rejected from the scheme, you should see if the reason you were rejected is something you can change (for example, if you needed to have a Green Deal assessment carried out.) If it is, you can simply reapply once you are confident the reason for rejection has been resolved.

If you were rejected prior to passing the identity check you will not receive a ‘MyRHI login’. Therefore you will need to reapply starting with the initial eligibility questions again.

If you were rejected at review, having passed the identity check you will have been given a ‘MyRHI account’. Login to this account and re-apply using the ‘additional application’ tab for a more streamlined application process.

If your application has been rejected, you retain the right of review. This means that if you believe your application has been wrongly rejected, you may apply to have that decision reviewed by us. For more information, please see the right of review section in this guide.


Approval under the Non-Domestic RHI

You can't seek approval for a heating system under both the Domestic and Non-Domestic RHI schemes. If you have been approved under the Non-Domestic scheme you can't apply for the Domestic scheme for the same heating system, and you can’t cancel your application once you've been approved or switch schemes.

This means, if you’ve submitted an application to the Non-Domestic RHI scheme, it has been approved, but you withdraw it, you cannot apply to the Domestic RHI instead, even if you installed a different heating system or vice versa.

If you have been rejected under the Non-Domestic RHI scheme you can still apply to the Domestic scheme. You will need to meet the Domestic RHI eligibility criteria, so you should read the Essential Guide for Applicants prior to making an application.

If you have made an application for the Non-Domestic scheme, but have not been approved, you may withdraw your application and apply for the Domestic scheme.

You can’t apply for the Domestic RHI if there is a heating system approved under the Non-Domestic RHI already installed in the property which is covered by the domestic EPC, or if a Non-Domestic RHI system supplies heat to the domestic property.

Because the scheme is funded by public money, this is to prevent double subsidising.

If you think that you aren't eligible for the Domestic RHI, but that you may meet the criteria for the Non-Domestic RHI, please see the Non-Domestic RHI guidance documents for further information.


Assignment of Rights

The Government has introduced changes to the Domestic RHI Regulations in two stages. The first stage of changes to the Domestic Scheme came into force on 20 September 2017. The second stage of changes came into force on 22 May.

For more information about changes to the scheme and what they mean to you, please see our changes to the scheme webpage and our Factsheet: Important changes to the Domestic RHI Scheme.

What is Assignment of Rights?

Assignment of rights is an option to help householders and organisations access finance to overcome the upfront cost of a renewable heating system. This option allows an investor to assist in meeting the costs of the installation of a domestic renewable heating system for households and/or organisations. Households and organisations are then able to assign their rights to RHI payments to “nominated” investors.

Applicants must be the owner of the renewable heating system at the application stage and throughout the RHI membership. Investors aren’t permitted to own any part of a plant for which they will be nominated to receive payments. Both participants and investors will have to comply with their ongoing obligations and responsibilities if accredited onto the scheme. 

If you’re an applicant

The application process follows a similar process to regular applicants to the Domestic RHI. During your application process, however, you can choose to assign your RHI payments to a registered investor. If your application to the Domestic RHI Scheme is successful, your registered investor automatically becomes your nominated registered investor; no action is required from you or your investor.

For full details on what you need to provide and your responsibilities, please read the Essential Guide to Assignment of Rights.

If you meet all scheme eligibility requirements, you may become a participant under the Domestic RHI Scheme. You must then comply with your ongoing obligations and responsibilities. If you fail to comply with the scheme rules, Ofgem may withhold payments to your Nominated Registered Investor and revoke your membership on the scheme. 

If you’re an investor

If you want to enter an Assignment of Rights agreement with an applicant, you as an investor must join either The Renewable Energy Consumer Code (RECC) or the Home Insulation and Energy Systems Contractors Scheme (HIES) to become a Registered Investor and agree to their terms. For more information about the codes see the Consumer Protection Codes

You can only be nominated for RHI payments by an applicant once you are a Registered Investor. Investors aren’t permitted to own any part of a plant for which they will be nominated to receive payments at application stage and throughout the RHI membership. 

Investors will be required to provide a current copy of the contract with which they intend to enter into assignment agreements with applicants*. The contract(s) must fulfil the relevant consumer code’s requirements. Ofgem will not be able to grant registration to the scheme until suitable assessment of the contract has been completed by the relevant consumer code. 

If you and your applicant’s assignment nomination is successful, you automatically become their Nominated Registered Investor and RHI payments will be made directly to you. Please note that only RHI payments can be assigned; participants cannot assign their Metering and Monitoring Service Package (MMSP) payments.

Once you become a Nominated Registered Investor, you must comply with your ongoing obligations and responsibilities under the Domestic RHI scheme. If you fail to comply with the scheme rules, Ofgem may withhold all or part of your payments of your assignments and/or revoke your registration. 

*A model contract will be available on RECC and HIES’s website at a later date

For further information, please see our Essential Guide to Assignment of Rights.


There are two types of audits on the Domestic RHI - desk audit and site audit. Below you will find what they consist of, and what is required of you.

Desk Audit

As part of our scheme compliance checks, a certain number of applications for accreditation to the scheme will be automatically subject to a desk audit. In these cases, we may need you to provide additional information as assurance that the heating system is eligible and that the application is otherwise compliant with scheme rules.

Also, a number of properties and plants will be subject to a desk audit after accreditation, as part of our regular compliance checks.

Some domestic plants and properties may also be subject to a desk audit where we have indications of fraud.

You may also be asked to provide further evidence of your compliance with the scheme rules, for example:

  • MCS certificate and MCS Compliance Certificate,
  • photographic evidence relating to the renewable heating system and/or meter(s),
  • copies of utility bills, council tax bills, tenancy agreements (for landlords),
  • copies of correspondence relating to Grantsopen key term pop-up,
  • a copy of the Installer Metering Questions (IMQs) for biomass or heat pumps if applicable,
  • proof of purchase and installation (eg invoices or receipts),
  • Biomass sustainability and the Biomass Suppliers List (BSL)open key term pop-up approved fuel receipts for all fuel which is solid biomass used in a scheme accredited heating system on or after 5th October 2015,
  • Standard and/or alternative metering schematic drawing,
  • solar thermal domestic hot water calculations,
  • title deeds, TR1 forms, fixtures and fittings or evidence of property ownership,
  • copies of relevant bank statement and ID documents.

This list is not exhaustive. We may ask for other evidence as necessary as part of the audit.

Please note that, even though you may have submitted some of these details above during the application stage, you will still be required to comply with the audit request and provide copies of these.

The Audit and Counter Fraud team have the authority to suspend your payments if you do not comply with your ongoing obligations. For more details, you can read about your ongoing obligations on our website.

Site Audit

We will select a number of sites for inspection by us or a third party on our behalf. During this visit, information about the accredited plant and property will be collected in order to verify the eligibility of the renewable heating system and to check overall compliance with the scheme rules.

A site audit is a physical inspection of the renewable heating system, at your property. We will need to inspect the renewable heating system, supporting infrastructure, and any buildings that may be connected to your plant.

Access requirements for site visits

If you’re a member of the scheme you will be required to comply with an ongoing obligation to permit us access to the domestic property for the purposes of inspecting your heating system.

If you own a renewable heating system but do not live in the property (eg landlords or Registered Social Landlords), it’s your responsibility to make sure that all of your tenants of the property/ies have agreed to permit us or our site auditors access to your property.  It’s an ongoing obligation under the scheme rules that you have that agreement.

If the auditor is not permitted access to the property (and the reason for refusal wasn’t sufficient), or isn’t permitted to investigate fully, this will be treated as a non-compliance. The Audit and Counter-Fraud team have the authority to suspend your payments if you don’t comply with your ongoing obligations.

If a site audit is required, we’ll provide you with a notice of an inspection a reasonable amount of time before the audit takes place. We generally expect the audit to be carried out within 28 days from receipt of the notice, at a reasonable time for you or your tenants. Site audits are usually carried out during business hours – 9:00 to 17:00 on weekdays.

In exceptional cases, advance notice may not be provided. All site auditors will carry identification, and a phone number will be provided which can be called to verify the identity of the auditor.

For more details, you can read about your ongoing obligations on our website.


Only grants that relate to the purchase or installation of your heating system are relevant to the Domestic RHI. Any public grant funding will be deducted from your Domestic RHI payments. More.

Biomass sustainability and the Biomass Suppliers List (BSL)

Sustainability criteria for the Renewable Heat Incentive (RHI) were introduced on 5 October 2015 for all installations using biomass fuels. More.