How to calculate N.I contributions per month

PaulStat · 3 Feb 2012 at 21:14

I mean without using online calculators like listen to taxman. I've found the following on the direct.gov.uk website

if you earn more than £139 a week and up to £817 a week, you pay 12 per cent of the amount you earn between £139 and £817

if you earn more than £817 a week, you also pay 2 per cent of all your earnings over £817

So that's ok I have an excel formula that looks a bit like this

Code:

NI per week = (((Annual salary/52) - 139) * 0.12)
NI per month = NI per week * weeks in a month

So say for December I use 4 weeks in the month (I know it's a bit more), the above comes up with a value of £227, on the actual pay slip it was £216, the listentotaxman calculator also has £216. So I'm obviously missing something?

[FnG]magnolia · 3 Feb 2012 at 21:16

You're missing 11 pounds.

You're welcome.

Participant · 3 Feb 2012 at 21:34

Do you earn £23,850?

Just wondering if the 53rd tax week for odd days is throwing things out.

Mercenary Keyboard Warrior · 3 Feb 2012 at 22:37

There is a monthly NI rate as well iirc

Mercenary Keyboard Warrior · 3 Feb 2012 at 22:40

think this may help

http://www.macintyrehudson.co.uk/tax/tax-rates-and-allowances/national-insurance-contributions

PaulStat · 3 Feb 2012 at 22:59

Right figured it out, apparently I had to take into account child care vouchers, so 243 out of my pay per month pre tax.

Code:

Salary per week = Annual salary/52
Child care per week = (243*12)/52 = 56.08
NI per week = (("salary per week" - "child care per week" - 139) * 0.12) = 49.98
NI per month = NI per week * average weeks in a month = 49.98 * 4.33 = 216.39