Help with tax codes

[AnotherOne4]

My boss informed me today that he had been notified my tax code has changed. This is the first I knew about this.
Upon coming home and checking some wage slips, I have been using 1185T. But I received a letter from HM Revenue in January this year, telling me my tax code for 6th April 2019 to 5th April 2020 is 1250T.

What does this mean, and what do I do now?

1185 was the standard tax code for 2018/2019 for the personal allowance, to tell your payroll people that you could earn £11850 per year before paying any tax.

For the year 2019/2020, the personal allowance has gone up to £12500, so now your tax code is 1250T, but I don't know what the T means or if the letters after can be different.

Does your boss do the payroll and has he not employed anyone before? Anyone who is experienced in payroll should recognise the significance of those numbers instantly, although I don't know if HMRC send out coding notices for people on the standard allowance although they do for people with company cars or other allowances/deductions, eg second jobs or possibly childcare vouchers.

So that must mean I've been paying too much tax since April this year?

Yes, if the 1185 is on your payslip for April onwards, but it will even out by the end of the tax year, but it probably won't be much - a tenner a month or something.

It will even out in your next pay period as tax is cumulative for the year.

Ahh ok, thank-you :)