Net salary calculation in the UK

Question

I have a hard time trying to understand how net salary is calculated when you work in the UK.

I have used this calculator to find out my net monthly salary based on the gross amount, and it just gives me one number as my annual net, and monthly net is just annual/12. But in reality it seems to be more complicated: for example, different tax rates apply depending on how much you have earned so far this year.

Assuming for simplicity that I have £100k yearly gross salary, no pension or other deductions, and I came to the UK and started working in January 2019, can someone please help me fill out this table?

┌───────────────┬─────────┬────────────────────────────┬───────────────────────┬───────────────────┐
│     Month     │  Gross  │     National Insurance     │          Tax          │        Net        │
├───────────────┼─────────┼────────────────────────────┼───────────────────────┼───────────────────┤
│ January 2019  │ 8333    │ 471                        │ 0                     │ 7861              │
│               │         │                            │                       │                   │
│ Calculation   │ 100k/12 │ ((weekly gross up to £962  │ No deduction beacuse  │ 8333 - 471 = 7861 │
│ details       │         │  - untaxable limit) * 12%) │ yearly gross so far   │                   │
│               │         │  + remainder * 2%          │ is less than 12500    │                   │
│ ------------  │ ------- │ -------------------------- │ --------------------- │ ----------------- │
│ February 2019 │ 8333    │ 471                        │ ???                   │ ???               │
│ ...           │         │                            │                       │                   │
│ ...           │         │                            │                       │                   │
│ January 2020  │         │                            │                       │                   │
└───────────────┴─────────┴────────────────────────────┴───────────────────────┴───────────────────┘

I am basically trying to understand how much money I will have in my bank account every month.

Answer 1

Assuming you are paying tax via pay as you earn (PAYE) indeed, the monthly net income should be the annual net income divided by 12. You seem to have been confused by the personal allowance. Yes, the "first £12,500" you earn in a year is "tax free", but in order to avoid pay cheques varying month-to-month, HMRC estimates how much your annual income will be and give you a tax code which instructs your employer how much of your salary to withhold as income tax and national insurance contributions. The result of this should be that an equal amount of tax is withheld from you every month. You can imagine that the tax free allowance is spread equally over the whole year. So you would get about £1041 "tax free" each month.

When you start at your job, your employer should inform HMRC what your salary is, and HMRC will tell your employer and you what they think your tax code should be. Errors in tax estimation can happen, particularly if you have changed employer. If you end up paying too much or too little tax, HMRC will either change your tax code to account for it, or send you a bill or a cheque.

Answer 2

The Government calculator you linked to seems to provide valid answers ... With a salary of 100k/year (your gross salary), the result is £5544 in your bank every month:

==> Your estimated take-home pay for 2019 to 2020 is *£5,544.95 a MONTH*

Based on the information you’ve given us:

 * your Income Tax is £2,291.37 (per month)
 * your National Insurance is £497.01 (per month)
 * in total you pay £2,788.38 (per month)

How we calculated your results:

 * Your pay is £8,333.33  (per month) (you told us this)
 * Your tax-free allowance is £1,042.41  (per month)
 * Your taxable pay is £7,290.92 (per month)