Income tax question

[parttimebored]

I have started a new part time job and earn just below the income tax threshold (£11,500) . There is plenty of overtime available but I'm wondering what happens to in regards to income tax ? Do I need to earn a total amount of £11,850 within the tax year before I am taxed or if I do overtime , will any additional hours be taxed ?

You are taxed on the part of your earnings over the tax threshold

and you'll pay NI on any monthly earnings over the £8600 / 12 limit

Yes as above. Divide the 11850 by 52 for weekly or 12 for monthly and you will pay tax on the amount you earn above that amount in that period.

So do I need to earn 11850 in a tax year before i am taxed ? For example, can I do 20 hours of over time this month and so earn £1200 and still not be taxed as I haven't yet reached 11850 this year ?

Yup
tax is cumulative
so you can earn masses one month without a tax bill if there is zilch in the following months
BUT
you will get hit for NI if you earn more than £650 in any one month through PAYE

Ok I think I've got it now. Thank you

Whatever happens, at the end of the tax year you can check to see if the total amount of tax paid is right and hmrc will give you a refund if not.

If your normal salary is £500 below the tax threshold and you earn £500 in one month then you could end up paying some tax that isn't due and will be refunded but not for a few months.

But all in all don't be afraid of paying a little tax. If you earn £500 above the threshold over the year you get to keep £400 of it as well as the £11,500 which is untaxed, and your employers send £100 to fund schools, hospitals and pensions and all the other things that make it nice to live in a civilised society. That's a good thing.

It is cumulative on a monthly basis, assuming you are on a standard tax code with no M1 (month 1) on it.

So;
April = personal allowance ÷ 12. Compare to income for the month, pay tax on any excess.
May = personal allowance ÷ 12 x 2. Compare to income for April & May. Pay tax on any excess less tax already paid for April.
June = personal allowance ÷ 12 x 3. Compare to income for April, May & June. Pay tax on any excess less tax already paid for April & May.
Etc
So if you did loads of overtime in April you would get taxed, if you did none for the rest of the year you would recoup that tax over the course of the year if you are under the personal allowance in total by the end of the year.
If you did no overtime all year then did some in March you probably wouldn't get taxed (depending on the figures).