Summary
If you make £1,261,000,000 a year living in United Kingdom, you will be taxed £608,415,161. That means that your net pay will be £652,584,839 per year, or £54,382,070 per month. Your average tax rate is 48.3% and your marginal tax rate is 48.3%. This marginal tax rate means that your immediate additional income will be taxed at this rate. For instance, an increase of £100 in your salary will be taxed £48.25, hence, your net pay will only increase by £51.75.
Bonus Example
A £1,000 bonus will generate an extra £518 of net incomes. A £5,000 bonus will generate an extra £2,588 of net incomes.