Self Assessment penalties

[TIMONLINE]

Do self assessment penalties kick in straight away or is there a month's grace (as I thought I'd read somewhere)? For example if I pay part of my SA payment, on 10th Feb will I incur any penalties or interest charges?

[pawncob]

There is no period of grace.

http://www.hmrc.gov.uk/sa/deadlines-penalties.htm

[TIMONLINE]

So what penalty would be due in I paid on 10th Feb?

[RAL]

It is in the link provided in previous comment. If it is paid by 30 days late then 5% penalties. As you are paying on 10th then you will incurred some interest on late payment.

Have a look at the link provided at bottom of page, "interest and penalties if you don't pay your tax on time"