The mileage rate for business miles above 10,000 will rise from 25p to 35p per mile under the government's pre-Budget package, MoneyWeek reports.
The change is part of the package of measures announced ahead of Wednesday's Budget, which also removes import tariffs on more than 100 products. Earlier reports had listed the mileage change without giving a figure.
The government says the change will help three million people who use their own vehicle to travel for work, according to MoneyWeek. That claim has not been independently checked.
MoneyWeek also gives more detail on the change to carer's allowance. It reports a weekly earnings limit of £204, with a £1-for-£1 taper above that level replacing the cliff-edge.