New number plates in March and September

One plate change a year became two

Under the suffix and prefix schemes the age letter changed once a year, on 1 August for most of that period. The effect was a market that did roughly a quarter of its annual business in a single month.

That concentration was bad for everybody. Manufacturers had to build to a peak they could not sustain, dealers had to staff for it, transport and registration systems strained under it, and buyers who wanted a car in June were pushed into waiting eight weeks for a newer letter.

The current scheme, introduced in September 2001, changes the identifier twice a year instead. The spring identifier arrives on 1 March and the autumn one on 1 September, which splits the peak into two smaller ones.

What that means for a new car buyer

The two plate change months are still by far the largest for new registrations in Britain, and that is where the pressure sits. A dealership with a registration target has more room to move in the last week of a plate month than at any other point in the quarter.

The month before a change is the other useful window. Stock registered on the outgoing identifier becomes harder to shift the moment the new one arrives, so a car sitting on a forecourt in late February or late August is a car somebody wants gone.

The opposite is true for a buyer who wants the newest plate. Demand for a fresh identifier is highest in the first fortnight of March and September, which is the worst moment to negotiate and the best moment to be told the waiting list is long.

• Best time to negotiate on a new car: the closing days of March, June, September and December.
• Best time for a discount on outgoing stock: late February and late August.
• Worst time to negotiate: the first two weeks of March and September.

What it does to used values

The identifier is a shorthand for age, and the used market prices it accordingly. A car on a 24 plate reads as older than one on a 74 plate even where the two were registered six months apart and have covered the same mileage.

That produces a small but real step in value at each plate change, and it is worth knowing when you are part exchanging. A car sold in late August on a 21 plate is competing with a wave of 71 plate cars arriving in September, and the same car sold in July is not.

The step is largest on cars up to about four years old, where the plate is the first thing a buyer reads. Beyond that the mileage and the condition dominate, and the identifier stops carrying much weight at all.

The quiet months, and why they matter

Between the two peaks the market is thin. January and February before the March change, and July and August before the September change, are consistently the quietest months for new registrations.

A quiet month is a buyer's month on both sides of the transaction. There is less competition for the car you want and less competition for the car you are selling, because fewer people are moving at all.

It also affects delivery. A factory order placed in a quiet month is usually built and delivered faster than the same order placed six weeks before a plate change, when everybody in the country wants the same thing at the same time.

Ordering around the change

A factory order placed in the six weeks before a plate change joins a queue that everybody else is in. The same order placed in a quiet month is usually built and delivered faster, because the line is not running flat out to hit two dates a year.

If the identifier matters to you, the thing to agree in writing is the registration date rather than the delivery date. A car delivered on 28 February wears the outgoing identifier for the rest of its life, and a dealer under pressure to clear a month will sometimes register a car before you take it, which is worth asking about directly.

If the identifier does not matter to you, that is a lever. A car already registered on the outgoing identifier is a car the dealer is now motivated to move, and the discount on one is usually larger than anything available on an order for the new plate.

• Agree the registration date in writing, not just the delivery date.
• A pre-registered car is cheaper and is one identifier older from the day you get it.
• Delivery is quicker in a quiet month than in the run-up to a change.

What the identifier does not tell you

The identifier records the date the mark was issued, not the date the car was built. A car registered on 1 March may have been built the previous November and stood in a compound since.

It also does not survive a private plate. A registration may never make a car appear newer than it is, but it may make it appear older, so a 24 plate car wearing a dateless mark loses its identifier entirely.

Where the age genuinely matters, the field to read is the date of first registration on the V5C. It is also on the free DVLA vehicle enquiry service, and it is the date every tax and emissions rule is decided by.