HELP - Tax Allowence for single parent but now Im Married

Hi,
This might sound as If I am so stupid but bear with me Im not...

I have a (single parent) tax credit for my son who is now 9 yrs of age which amounts to the doubling of the regular single tax allowence.
My son is from a previous relationship (non marriage) and I have been claiming this allowence since he was 1 .
He lives with his mother.

It has only dawned on me that this credit is still on my tax Cert even though I am now married for the past 14 months to my beautiful wife.
This only came to light when I was looking to see what changes I might make to my tax credits seen my wife is on maternity leave with our new son.....I have not informed revenue of the following...
(a) I am married
(b) My status has changed (ie) no longer single parent to my eldest son.

Can someone out there in the abyss please tell me if I am screwed (ie) owe a big tax bill since the day I was married .
Should I tell the revenue anything.

Your help is needed .

Thanks.

You cant claim single parent relief when you are married so you should stop it now and pay back what you owe...was the childs mother not claiming the single parent tax relief seen as though the child lived with her.

The one parent family tax credit is also not available when co-habiting, so if you lived with your wife (or any other girlfriend) before your marriage then you will need to repay the credit for that period too.

You really need to contact Revenue as soon as possible to sort out the matter, they may be more lienient with you for coming forward as soon as you discovered the problem.