What do I put in V55/5 box 34 cylinder capacity?
Reviewed 2026-07-10
Short answer
Put the cylinder capacity in cc, using the CoC or manufacturer evidence. If the engine has changed, use evidence for the current engine.
Official position
The V355/5 guidance says box 34 is cylinder capacity in cc and tells applicants to take it from the Certificate of Conformity or get it from the vehicle manufacturer.
What to do
Use the CoC, approval certificate, manufacturer data, foreign document or reliable engine evidence.
Make sure capacity agrees with the current engine number and vehicle evidence.
For motorcycles, capacity can affect tax class and rate, so do not round casually.
For electric vehicles with no cylinder capacity, follow the form and guidance route for your vehicle type rather than inventing a cc value.
Common mistakes
- Entering litres instead of cc.
- Using the old engine capacity after an engine swap.
- Rounding a motorcycle capacity into the wrong tax band.
Related help
Official sources
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