If you make £120,000 a year living in United Kingdom, you will be taxed £41,758. That means that your net pay will be £78,242 per year, or £6,520 per month. Your average tax rate is 34.8% and your marginal tax rate is 42.0%. 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 £42, hence, your net pay will only increase by £58.
A £1,000 bonus will generate an extra £580 of net incomes. A £5,000 bonus will generate an extra £2,900 of net incomes.
NOTE* Withholding is calculated based on the Great Britain tables of United Kingdom, income tax. For simplification purposes some variables (such as marital status and others) have been assumed. This document does not represent legal authority and shall be used for approximation purposes only.