The 2018/19 rates will be:

• Income up to £11,850 - 0% income tax. This is your personal tax-free allowance. 
• Income between £11,850 and £46,350 - 20% income tax
• Income between £46,351 and £150,000 - 40% income tax
• Income above £150,001 - 45% income tax

The personal allowance will reduce by £1 for every £2 you earn over £100,000. So, by the time you earn, £123,700, you'll pay income tax on everything you earn and get no personal tax-free allowance.

http://www.telegraph.co.uk/money/consumer-affairs/budget-much-income-tax-will-pay-personal-allowance-goes/