Hi I have a yearly income of 30000£ in UK, this is my first job and my tax code is 1210 L. I didn't get taxed for the first month. Could anybody please let me know whether I need to change tax code to pay tax? Also I would need to know how much I would be taxed after the threshold and how much I would receive as my take home salary. I don't have any pension deductions. Thanks
It's to be expected that you won't get taxed for a few months. Because this is your first job this tax year, and tax is calculated cumulatively over the course of a whole tax year, you have a lot of "unused" personal allowance from April.
As 24601 said this tax year, you'll ultimately get taxed on about £2900 (15K-12100), and will pay a bit under £600 in tax. Most of that will be taken in February and March. Then from April 2022, you'll pay a "normal" amount of tax each month - with earnings of £2500/month and a personal allowance of about £1000/month, that'll be tax of £300/month.
As 24601 also said, on top of the tax you'll pay National Insurance contributions, but that should be already happening as they are calculated on a weekly/monthly basis.
It may not be a problem at all.
The current free tax allowance (2021/2022 tax year) in the UK is £12,570 which is the basic rate - this would normally give a tax code of 1257L
Your tax code may be different if you have already underpaid tax to HMRC as they may adjust the code downwards in order to recover any underpayment.
The tax code works cumulatively and you can be assured that your employer will correctly apply the code to earnings. It's entirely possible that your first salary was paid before they obtained the appropriate paperwork from HMRC authorising them to make the deduction but there will be a catch-up probably at your next pay date.
If you have any concerns about your tax status you can do your own checks by referencing https://www.gov.uk/tax-codes which is the only reliable way forward.
For reference, these are the UK tax bands:
so you will normally expect to pay 20% tax on income above £12,570 (the normal personal allowance) to £50,270 although in your case, it would seem that you will only have a (currently unexplained) tax free allowance of £12100
As to your question about likely take home pay... consider that earning £30k pa will realise (£30,000 ÷ 12 * 6 months Oct21 - March22) = £15,000 against the free pay amount (assumed at £12100 in your example) for the whole tax year or put another way £15000 - £12500 = £2500 on which tax will be due at 20% ie ⅕th of your monthly pay will be taken in income tax.