Can I use an ADHD diagnosis letter for the Disability Tax Credit?

No, a diagnosis letter cannot stand in for Form T2201

A diagnosis letter confirms that a licensed clinician assessed you and found that you meet the criteria for ADHD. The Disability Tax Credit (DTC) asks a different question: how much your impairment restricts everyday mental functions, how often, and for how long. The Canada Revenue Agency (CRA) answers that question from Form T2201, the Disability Tax Credit Certificate, not from a letter you attach.

Form T2201 has two parts. Part A is completed by you or your legal representative, online in your CRA account, by phone or on paper. Part B can only be completed by a medical practitioner, who certifies the effects of your impairment and the year they began. CRA reviews both parts and makes the decision.

So the honest answer is that the letter is supporting material. It can help the practitioner who certifies Part B, and it can help you explain your history. It does not go to CRA in place of the form, and CRA does not approve the credit because a diagnosis exists.

CRA judges the effects on ten mental functions, not the diagnosis

CRA's own wording is direct: eligibility for the DTC is based on the effects of an impairment, not a diagnosis or the presence of a medical condition. For ADHD, the relevant category is mental functions necessary for everyday life. The certifying practitioner has to describe restrictions in these functions:

• Adaptive functioning, such as managing basic needs and taking part in the community
• Attention, including awareness of danger and impulse control
• Concentration, such as focusing on a task and recalling information
• Goal-setting, meaning making and carrying out simple plans
• Judgment, including recognizing risks and making appropriate decisions
• Memory for personal information, instructions and important details
• Perception of reality
• Problem-solving in everyday situations
• Regulating behaviour and emotions
• Verbal and non-verbal comprehension

Three tests apply at the same time. The restriction must be marked: you cannot perform the function, or it takes you three times longer than someone of a similar age without the impairment, even with appropriate therapy, medication and devices. It must be present all or substantially all of the time, which CRA describes as generally 90 percent or more. And it must be prolonged, meaning it has lasted or is expected to last for a continuous period of at least 12 months.

That is why two people with the same ADHD diagnosis can get different decisions. A well-documented diagnosis with moderate day-to-day impact may not meet the threshold; a diagnosis paired with marked, near-constant restriction in attention, concentration or regulating behaviour might. The letter tells CRA nothing about the second half of that sentence. Part B does.

Nurse practitioners, physicians and psychologists can certify the mental functions section

Part B must be completed by a medical practitioner that CRA recognizes for the category being certified. For mental functions, three professions qualify, and a nurse practitioner is one of them.

Being permitted to certify is not the same as being obliged to. A practitioner signs Part B only when their own findings support marked, prolonged restriction. If a clinician tells you the criteria are not met, that is a professional opinion about the CRA threshold, not a comment on whether your ADHD is real.

Finding Focus clinicians can complete DTC paperwork when the criteria are met, as described in what ADHD documentation you can get for work or school. For the background on the credit itself, see what the Disability Tax Credit is for ADHD.

Where your letter or report does fit into a DTC application

The letter and report earn their place before Part B is signed, not after. A practitioner who did not assess you, such as a family doctor you have seen for years, may be willing to certify but wants to see the diagnostic basis first. The $99 healthcare-provider report summarizes the assessment, the DSM-5-TR criteria that were met, the diagnosis and the treatment plan, which is exactly the record a certifier wants in the chart before describing effects.

• Give the certifier the report, not just the letter, when they were not the assessing clinician
• Bring your own examples of the ten mental functions in daily life, with how often they happen and how long tasks take you compared with other people
• Ask the certifier to record the year the marked restriction began, because CRA uses the certified start year when it sets the eligibility period
• Keep the letter for employers or schools; CRA does not need it

If the nurse practitioner who assessed you is also the certifier, the report is already part of their record, and you can go straight to asking whether Part B is appropriate in your case.

Certification has a fee, CRA may ask the practitioner questions, and CRA decides

CRA states that if your medical practitioner charges a fee for completing the DTC application, you are responsible for paying it, and that you may be able to claim the fee as a medical expense on your tax return, on line 33099 or 33199. At Finding Focus, document-preparation fees are shown at the time of request in your patient portal.

After Part B is submitted, CRA reviews the application and may contact the practitioner for clarification, so the certifier's clinical notes matter as much as the form. You receive a written decision. If approved, the federal disability amount for the 2025 tax year is $10,138 for a person aged 18 or older, claimed on line 31600; provincial and territorial amounts are separate. If refused, the decision letter explains how to ask CRA to review it.

DTC approval is also the gateway to other programs, including the Registered Disability Savings Plan (RDSP), the Canada Disability Benefit, the child disability benefit and the disability supplement to the Canada Workers Benefit. If those are your real goal, plan the T2201 route from the start rather than collecting letters. If you have not been assessed yet, an online ADHD assessment is where you find out whether you have ADHD at all; the free screener at /get-started/ is a screening step, not a diagnosis.