DVLA Medical & CDT Test Guide

CDT Test DVLA – Medical Drink Driving Examination

The DVLA CDT blood test is mandatory for high risk drink driving offenders before a driving licence is reissued after disqualification. This guide explains exactly what the test involves, the pass thresholds, what happens if you fail, and how to get insured once your licence is restored.

1.6%

CDT pass threshold
for alcohol dependent drivers

90days

Before ban ends
when you can apply

15days

DVLA decision target
if no further enquiries needed

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Updated March 2026

10 min read

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What Is the DVLA Medical Test? What Is Included? CDT Test Levels How to Pass the CDT Test D1 and D27 Forms What Causes a Failure? What Happens If You Fail? Right to Appeal DR10 Insurance Contact the DVLA

What is the DVLA medical drink driving test

The DVLA medical drink driving test is in place to make sure each driver who has had their driving privileged suspended for an alcohol related offence are now fit to drive a vehicle once their suspension has expired. The CDT Test DVLA is required when the suspended driver is reapplying for their driving licence because they are classified as high risk.

If you have been convicted with a drink driving conviction, you will find getting convicted driver insurance both difficult and expensive. We can help you to get multiple insurance quotes to help you start your journey back behind the wheel.

For drink driving the disqualification can stay on your licence for 12 months or more, depending on the severity of the conviction. 90 days before the suspension is to end, a person can begin the process of obtaining a driving licence by filling out and submitting a D27 form.

Once the DVLA office receives the form, a doctor is chosen to conduct the medical examination. The details about the exam are sent to the applicant and will include the doctor’s name and the location of his office. It is the responsibility of the applicant to schedule the appointment with the doctor. There is a fee for this test and must be paid at the time of the exam.

What is Included in the Medical Test?

The medical exam has three parts to it.

Physical medical exam to assess whether the applicant has the motor skills and physical ability to operate a vehicle. Doctors may also ask questions to evaluate mental fitness.
A carbohydrate-deficient transferrin (CDT) blood test is required. This biomarker detects recent alcohol consumption. To pass, the CDT result must be 1.7% or below. Results are typically available around 15 days after the sample is submitted.
Completion of a written questionnaire (the DR1 Form ), which can be filled out online. The information provided helps determine whether the applicant is mentally ready and safe to operate a vehicle again.

What Are the DVLA CDT Test Pass Levels?

The DVLA CDT pass level is 1.6% or below for drivers with a history of alcohol dependence, and 2.2% or below for drivers with a history of alcohol misuse or no history at all. A result between 2.3% and 2.9% triggers further enquiries with your GP. A result of 3% or above means your licence application will be refused. The DVLA uses a traffic light system of green, amber and red to assess results, and the threshold that applies to you depends on your personal history of alcohol use.

Green — Pass

1.6% or below for drivers with alcohol dependence history. 2.2% or below for drivers with misuse history or no history. No recent problematic alcohol intake detected. Your licence is likely to be issued within 15 working days.

Amber — Further Enquiries

2.3% to 2.9% for drivers with no history of dependence or misuse. This range suggests possible problematic alcohol consumption. The DVLA will contact your GP before making a decision. This can extend the process by up to 90 working days.

Red — Refused

1.7% or above for drivers with alcohol dependence history. 3% or above for all other drivers. This level indicates alcohol dependency. Your driving licence application will be refused and a minimum waiting period will apply before you can reapply.

Your Personal History Changes Your Threshold

If you have a history of alcohol dependence, your pass threshold is stricter at 1.6% rather than 2.2%. The DVLA appointed doctor will know your background from the DR1 questionnaire you complete as part of the medical. Do not assume the higher threshold applies to you.

Full CDT Cut-Off Levels by Driver History

The table below shows the exact %CDT thresholds the DVLA applies for each driver category. These thresholds were correct at the time of publishing. The DVLA medical advisory panel can review and update them at any time.

Driver History	Result	%CDT Level	What It Means
History of alcohol dependence	Green	1.6% or below	No recent alcohol intake. Acceptable for licence to be issued.
History of alcohol dependence	Red	1.7% or above	Suggests recent excess alcohol intake. Licence will be refused.
History of alcohol misuse only (no dependence)	Green	2.2% or below	Acceptable as evidence of controlled drinking. Licence can be issued.
No history of dependence or misuse	Green	2.2% or below	Normal range. Little or no alcohol consumption. Compatible for licensing.
	Amber	2.3% to 2.9%	Possible excess or binge drinking. DVLA will contact your GP before making a decision.
	Red	3% or above	Indicates alcohol dependency. Licence refused.

Blood results are typically returned to the DVLA within one week of the sample being submitted. Once the DVLA has everything it needs, it aims to reach a decision within 15 working days for straightforward cases, or up to 90 working days if further investigation is required such as your GP being contacted for additional medical information.

What causes a failure in the DVLA Medical Test?

An applicant will fail the test if they are unable to show there has been no alcohol abuse in the past 6 months. They must also prove there has been no alcohol dependency in the past 12 months. The physical examination and the CDT test will expose the applicant to alcohol use. When the exam is failed, the applicant can reapply after waiting for a year.

The DVLA medical drink driving test is in place to help make the roads safer from those who have been convicted of drinking and driving. After the driving licence is obtained, a DR10 car insurance specialist should be contacted so the vehicle they will be operating will have insurance coverage. The DR10 endorsements on the driving licence for having a drink driving offence will be classified as spent after 5 years from the date of the conviction.

When you start searching for car insurance after a drink driving ban, expect to pay double what you were paying before the conviction. We have a panel of specialist insurance providers who are able to assist you in finding affordable insurance after a drink driving ban.

How to Pass the DVLA CDT Test

The only reliable way to pass the DVLA CDT test is to stop or significantly reduce alcohol consumption in advance of your medical. The CDT biomarker reflects alcohol intake over the previous 2 to 4 weeks, so the preparation window is relatively short but critical. There is no shortcut. The test is specifically designed to detect recent heavy or chronic alcohol use, and the DVLA appointed doctor will also assess you through a physical examination and the DR1 questionnaire.

What Does CDT Actually Measure?

CDT stands for Carbohydrate Deficient Transferrin. Transferrin is a protein in the blood that carries iron. When alcohol is consumed heavily or consistently, the carbohydrate chains on transferrin become deficient, raising the %CDT level. The test measures this percentage. It is considered more accurate than older biomarkers such as GGT and MCV, which the DVLA no longer uses.

How Long Does It Take for CDT Levels to Normalise?

CDT levels typically begin to fall within 2 to 4 weeks of stopping or significantly reducing alcohol consumption. For most people, levels return to the normal range within 4 weeks of complete abstinence. However, this varies depending on how much alcohol was being consumed, how long the pattern of drinking had been established, and individual factors such as liver health and metabolism.

If you have a history of alcohol dependence, normalisation may take longer and your pass threshold is stricter at 1.6% rather than 2.2%. In this situation, giving yourself as much preparation time as possible before the medical is strongly advisable.

Stop or Reduce Alcohol Consumption

Complete abstinence for at least 4 weeks before your medical gives CDT levels the best chance of returning to the normal range. The longer the abstinence period, the more reliable the result. If you are struggling to stop drinking, speak to your GP before your medical appointment.

Apply Early and Give Yourself Time

You can submit your D1 or D27 application up to 90 days before your disqualification ends. Applying early gives you the maximum preparation time and reduces the risk of delays leaving you unable to drive after your ban expires.

Consider a Private CDT Test First

Private CDT blood tests are available and allow you to check your own levels before the official DVLA medical. This gives you an indication of where you stand and whether you need more time. See the section below on private CDT testing for more information.

Complete the DR1 Questionnaire Honestly

The DR1 form asks about your drinking history and medical background. The DVLA appointed doctor uses this alongside your blood results. Providing inaccurate information is not only a risk to your application but could have legal consequences. Answer all questions honestly.

Speak to Your GP in Advance

If you have concerns about your CDT levels, your drinking history, or how to prepare for the medical, your GP is the right person to speak to. They can advise on your individual situation, support you through the process, and may be contacted by the DVLA anyway if your result falls in the amber range.

Stay Well Hydrated on Test Day

Proper hydration on the day of your blood test makes the draw quicker and easier. Bring your photo ID and any DVLA paperwork you have received. Arrive on time as the appointed doctor may have a limited window for DVLA medical appointments.

Editorial Disclaimer

The information in this section is for general guidance only and does not constitute medical advice. CDT levels are affected by individual health factors that vary from person to person. If you have concerns about your alcohol consumption or your ability to pass the DVLA medical, you should speak to a qualified medical professional or your GP before your appointment.

How Do You Apply for Your Licence After a Drink Driving Ban?

To reapply for your driving licence after a drink driving disqualification, you need to submit either a D27 renewal form or a D1 application form to the DVLA. You can do this up to 90 days before your disqualification ends. Once the DVLA receives your application, they will arrange a medical examination with a DVLA appointed doctor in your area. You must then contact that doctor yourself to book the appointment and pay the medical fee on the day.

Do Not Wait for the D27 to Arrive

The DVLA should send you a D27 renewal form approximately 90 days before your ban ends, but forms often arrive late and sometimes do not arrive at all. If the DVLA is still processing your medical enquiries when your disqualification ends, you will be unable to drive until they declare you fit. Send your application as early as possible. You do not need to wait for the D27 to arrive — you can use a D1 form instead.

D27 or D1 — Which Form Should You Use?

Most high risk offenders receive a D27 renewal form from the DVLA. However if yours has not arrived, you can use a D1 application form for a car, moped or motorcycle instead. You can order a D1 form online from GOV.UK or collect one from your local Post Office. Complete the form and send it to the DVLA along with the appropriate fee and an up to date photo if one is required.

Step 1 — Submit Your Application

Complete your D27 or D1 form and send it to the DVLA up to 90 days before your disqualification ends. Include the required fee and a current photo if needed. Send by recorded delivery so you have proof of postage.

Step 2 — DVLA Appoints a Doctor

Once your application is received, the DVLA will write to you with the name and location of a DVLA appointed doctor in your area. It is your responsibility to contact that doctor and book your medical appointment. There is a separate fee payable to the doctor, usually on the day of the examination.

Step 3 — Attend the Medical Examination

The medical includes a physical examination, the CDT blood test and completion of the DR1 questionnaire. Bring your photo ID and any paperwork the DVLA has sent you. Blood samples are typically sent for analysis and results returned to the DVLA within one week.

Step 4 — DVLA Makes a Decision

Once the DVLA has your medical results, they aim to make a decision within 15 working days for straightforward cases. If further investigation is needed, such as contacting your GP for additional information, the process can take up to 90 working days.

Step 5 — Licence Issued or Refused

If the DVLA is satisfied with your results, your licence will be issued. In some cases a temporary one, two or three year licence may be issued rather than a full licence, particularly where there is a previous history of alcohol dependency but current results are satisfactory. If refused, you will be told what steps are required before you can reapply.

Section 88 Warning

If you were convicted and disqualified on or after 1 June 2013, you cannot drive under Section 88 of the Road Traffic Act 1988 while waiting for the DVLA to assess your fitness to drive after your disqualification has ended. You must wait until the DVLA has formally declared you fit to drive and issued your licence before getting behind the wheel.

GOV.UK Licence Reapplication

DVLA Processing Timeline at a Glance

Stage	Timeframe	Notes
Submit D1 or D27 application	Up to 90 days before ban ends	Do not wait for D27 to arrive. Use D1 if needed.
DVLA sends doctor details	Variable	DVLA can have a backlog. Apply early to avoid delays.
Medical appointment and blood draw	Booked by you directly with the doctor	Many doctors only conduct DVLA medicals on certain days.
Blood sample analysis	Approximately 1 week	Sample sent to laboratory after appointment.
DVLA decision — straightforward case	15 working days	From receipt of all medical information.
DVLA decision — further investigation needed	Up to 90 working days	If GP is contacted or medical advisors need to review.