Personal Allowance Less dividend tax

Hi all,

I'm new here and just looking for some advice.

I've had the annual letter through from HMRC regarding Tax code notice.

It states Total Tax free amount £9702 and tax code 970L

I Pay myself a basic £830.00 per Month and last year i took a dividend of £4995.00.

What i would like to know is why has my tax code changed? i asked my accountant and they said

it is because i received a Dividend on your last tax return and they are taxing you at source on this. This will always be the case until you don't receive a Dividend on your tax return.

Is this correct, i have no accountancy knowledge, but i thought i was allowed to earn up to £11500 without paying income tax and i could also take a dividend up to £5000 anything over the £5000 i would pay 7.5% or have i got this really wrong and my accountant is correct.

Thanks for any advice