Speeding motorists will face tougher penalties from today.

District judges and magistrates have been given new guidelines to follow which apply to all offenders aged 18 and over, regardless of the date of the offence.

The new law was issued on April 24 for up to 27 offences including speeding, sexual offences and drug offences where a new higher penalty will be introduced.

Fines for the most serious breaches will have a starting point of 150 per cent of a person's weekly income rather than the existing level of 100 per cent.

If someone is caught doing 41mph and above in a 20mph zone or 101mph on a motorway, where the limit is 70mph, they could be fined 150 per cent of their weekly income.

Fines are determined in categories - a Band A fine is 50 per cent of someone's weekly income, Band B is 100 per cent and Band C is 150 per cent.

The fines are ranked depending on how far in excess of the limit a driver is going.

There is a range, and anyone facing a Band C fine could see it upped to 175 per cent of their income.

Drivers will also face points, or a disqualification depending on the offence.