The UK's twin plate-change peaks: why March and September dominate registrations
The United Kingdom has two number-plate changes a year, and both show up as peaks. In 2025, March delivered 357,103 new-car registrations (17.7% of the full year) and September delivered 312,891 (15.5%), out of a 2,020,520 total (SMMT, full year 2025). Combined, the two plate-change months took about a third of UK passenger-car sales, a concentration similar in size to Ireland's January peak but split across two windows.
UK monthly share, 2024 vs 2025
| Month | 2024 share | 2025 share |
|---|---|---|
| January | 7.3% | 6.9% |
| February | 4.3% | 4.2% |
| March | 16.3% | 17.7% |
| April | 6.9% | 6.0% |
| May | 7.6% | 7.4% |
| June | 9.2% | 9.5% |
| July | 7.6% | 6.9% |
| August | 4.3% | 4.1% |
| September | 14.1% | 15.5% |
| October | 7.4% | 7.2% |
| November | 7.9% | 7.5% |
| December | 7.2% | 7.2% |
Shares are computed from SMMT's monthly passenger-car registrations: 1,952,778 cars in 2024 and 2,020,520 in 2025.
The plate-format mechanics
Britain's number plate carries a two-digit "age identifier". The March plate runs 25 in 2025, while the September plate flips to 75. Many buyers wait for the plate change so the car carries the newest identifier, which concentrates both private and fleet deliveries into those two months. The pattern has held since the current format launched in 2001.
Implications for the market
Two effects matter for anyone reading UK monthly data:
- Demand pull-forward and pull-back. February and August were the weakest months of both 2024 and 2025, at about 4% of the year each, because deferred demand moves into March and September. A weak February is a calendar effect, not a market signal. SMMT itself describes August as about 4% of annual registrations.
- EV-share volatility. Small months swing percentages more than big ones. In 2026, low-volume August reached a 29.8% BEV share, which SMMT called a recurring seasonal spike (SMMT, 4 September 2026). The September plate month, with far more volume, reached 28.3% BEV in 2026 on SMMT's preliminary figures, up from 23.3% in September 2025 (SMMT, 2 October 2026).
Source & methodology
Monthly registrations from SMMT (Society of Motor Manufacturers and Traders), the official UK new-car registration source. Light commercials and used-car sales are excluded; passenger cars only. The full 2015 to 2026 monthly series is available on the UK dashboard with brand and powertrain filters.
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