The Ultra Low Emission Zone (ULEZ) has now officially expanded across all of London.

The expansion means that all non-compliant vehicles, including cars, motorbikes, lorries and more will have to pay a daily charge of £12.50, even if travelling from Hertfordshire. 

With the ULEZ operating 24 hours a day, seven days a week, apart from Christmas Day, there is very little chance to avoid the fee. 

The ULEZ expansion has seen mass debate since London Mayor Sadiq Khan first announced the plans and even saw legal challenges from local councils and protests from local residents. 

Read more: ULEZ in Hertfordshire needs fixing - what can be done?

Many were unhappy with the charge, and some drivers have been sharing that they plan to avoid paying the £12.50 altogether. 

However, those who avoid paying the ULEZ charge, do face some penalties and even legal action.

Watford Observer: If may be best to pay the ULEZ charge.If may be best to pay the ULEZ charge. (Image: PA)

What happens if you do not pay the ULEZ charge?

Drivers entering the ULEZ have the option to pre-pay the fee or pay by midnight on the third day after the journey. 

However, if drivers choose not to pay the £12.50 daily rate, they could be met with a Penalty Charge Notice (PCN). 

A PCN will be handed out if you do not pay the ULEZ charge with a cost of £180 unless it's paid in 14 days where it will cost £90. 

But, if you do not pay the original PCN of £180, you will then be issued a Charge Certificate seeing the fine rise to £270 which you have 14 days to pay.

If you then do not pay the Charge Certificate, Transport for London (TfL) could seek further action with an Order for Recovery. 

An Order for Recovery means TfL will register that outstanding ULEZ charge as unpaid debt with the Traffic Enforcement Centre and will also mean your original charge will increase too. 

If drivers continue to ignore charges and notices, then the debt process will take place which could see bailiffs at your door. 

Alongside the potential of bailiffs, you may also be sent a Warrant of Execution which could be charged to you as well.