I've already read Pub 501 but my question isn't addressed there.

My girlfriend is disabled and I provide 100% financial support because she can't work. I would like to claim her as a dependent and add another allowance on my W4. Sometimes she *can* work but it depends on the nature of the job and her ever changing health. (Usually it's just short contracts.) We consider it a 50/50 chance she'll actually earn more than $3400 this year. For this reason I don't know if I can take that allowance on the W4 or not.

If she ends up earning more than $3400, do I simply have to settle up with the IRS at the end of the year? Or will they cry foul once they see her income and hit me with penalties on top of what I'd owe if she were never a dependent? (I've checked and she meets all the other requirements for dependency.)

Also, will the IRS object if I add an allowance to my W4 during the tax year and later remove it if my situation changes during that same year?

No, the IRS won't object if you change your W4 during the year.

I'm working on you other questions.

States vary and it would be best for you to go see a qualified tax consultant - any cheap tax service in your area would be able to answer this question (and provide assurance in case of audit). I don't think it would be smart to take advice from people in other states since California has different statutes on dependents and common law marriage than other states. I think that your dependent is disqualified if she earns more than the limit, and I think your tax return will be subject to audit and penalty if it's found that she has exceeded the limit for eligible dependent adult.

It's not something to mess around with unless you are certain it is valid to claim her.

Thank you both for your help and insights!

I did some research online and kept finding your question posted on other sites. I think you really need to contact the IRS and ask them. I agree with Ami that you need to seek a professional.

Telephone Assistance for Individuals:
Toll-Free, 1-800-829-1040
Hours of Operation: Monday – Friday, 7:00 a.m. – 10:00 p.m. your local time (Alaska & Hawaii follow Pacific Time).

Please repost an update. It may help someone else in a similar situation.