Can my spouse claim me and my children as dependents if he was still married?

Unless you had legal custody of them, he probably can’t claim them at all. A consultation with a tax attorney is probably in order.

I would think that legal marriage is a requirement to file a “married joint” return and get that rate of income withholding, but that’s different from the number of dependents. You can have dependents without being married – they are people who are financially dependent on you (and not being claimed by someone else). So I don’t think claiming you all as dependents would be the issue, but their might be a technical quibble about the married filing jointly. I don’t expect it will be a practical issue unless you get audited, though.

Editing out my answer. Reading others, I realized it was a duplicate, only not as good.

Are you married to this person now? If so, you do realize that in the U.S., its a criminal offense to be married to two people at the same time.

More info needed.

@john65pennington I am. He divorced his prior wife in 2007, then married me. But claimed me and my children for 2006. They were not living together or anything, but they were still married that year. I am sure she must have filed single- but he filed married- then put me as ‘spouse’ and my children as ‘son’ and daughter’.

Ask a tax consultant. But my guess is technically he was married to her so could file jointly but only if he included her income. Filing you and your kids as dependents is a separate issue and probably not a problem as long as no one else claimed you guys and dependents and you really were his dependents. However it sounds like he should probably re-file singly for 2006, and will probably owe money for that since it reduces how much income withholding he gets by a fair amount.