NI contributions Q ??

[CosmicG]

Is anyone any good at working out Ni contributions. I work 16hrs a week and my salary is £14560 pro rata. I calculated my monthly wage to be about £455. my weekly wage is around £105. I think this is right? What would my monthly NI contribution be?

The weekly primary threshold for NI is £149 per week so if you earn less than this you won't pay any NI yourself.

When you say, I wouldn't pay ot myself....does that mean it is paid ...but on my behalf?

If your weekly wage is below £109 (monthly around £472) then you're not covered for state pension for this period. I.e. for state pension purposes you may as well not be working. You will still get a year of state pension entitlement if you're claiming child benefit for children under 12 so it may not be a concern. You're also not paying any NI then.
If your salary is between £109 and £148 per week then neither you nor the employer is paying any NI but the year where you're earning at this level (or above, obviously) qualifies as one year for state pension entitlement.
Salary between £148 and £149 per week only your employer pays NI.
Salary between £149 and £797 per week means you pay NI at 12%.
On earnings above £797 a week your NI is 2%.

There are a number of sites where you can put your salary in and it will calculate any tax and NI due. Google "mranchovy PAYE" for one.

... But riksti's answer is correct and complete.

To work out the pro-rata salary you need to know what the full time salary is based on, but I am not sure if you have calculated this correctly.

If the full time basis is 37.5 hours a week then the part time pay is 16 divided by 37.5 times £14,560 divided by 52 which is about £119pw.

Thanks ritski and mr Anchovy. Very helpful answers.

i meant riksti