Joint assessment v single

I have read through threads here but I still cannot work all this out. My husband and I are assessed as single - I never really understood joint etc and whilst I think I did look into it when we were married, think I was told at the time to stay as we were.

We were married in 2003 - December. At the time my husband was on the higher tax rate - he was made redundant in May 2004 and was out of work until May 2005. He did not claim social welfare for the year he was out of work.

We are both now on the lower tax rate and my husband has been working since 2004 to date.

What are the advantages of being jointly assessed? People are now telling me that we should claim for the year he was out of work as I would have been entitled to his tax credits and would be due a refund of some sorts.

Is there an advantage to us being joint assessed? Can I claim anything for the year he was out of work? Would his tax credits have been adjusted when he took up employment again perhaps?

I know the above may be vague but I really don't know alot about this and am just throwing out the question which hopefully someone can help me with!

Thanks guys

I would write to Revenue outlining the position and requesting a balancing statment for 2005. Do it this week so that there is a paper trail that you made the request in the 2009 tax year. Claims can only go back 4 tax years, so the 2004 one is out already, and in 2 weeks the 2005 one will be too.