National Insurance now I'm married

[amummyinwaiting]

I know I am going to sound really stupid but....
I didnt know I had to change my details for my national insurance now that I am married. Its only because I requested a pack for seeing if I'm entitled to tax credits. They had my new address but my maiden name.
Iwork for the local council and so think payroll woul have told them new address.
So...it says on there website to write to them if you have had a change of name and gives an address.
What do I say in my letter?
Do I have to let any other departement in DWP know?
Are they goin to make me backpay extra tax because I'm married?

You seem to be confusing several different things

You are responsible for keeping HMRC and the DWP informed of all changes of name and address. Contrary to popular belief your employer does not tell the authorities when you change your details.

You need to write to both authorities quoting your National Insurance number and saying that you got married on [this date] and your name is now Mrs Waiting. You were previously Miss Bloggs.

Being married makes no difference to the amount of tax or NI you pay.

thank you!
Hate being so niave/stupid about things like this.
So I need to write to HMRC and DWP seperatly?
Thank you

I was told recently I needed to take my marriage certificate into the job centre for HMRC to recognise it. (I've been married 7 years so you're not alone - nobody tells you this!).