According to the IRS - see instructions for the form 5405 - http://www.irs.gov/pub/irs-pdf/f5405.pdf

You are considered a first-time homebuyer if:

-- You purchased your main home located in the United States after April 8, 2008, and before December 1, 2009.

-- You (and your spouse if married) did not own any other main home during the 3-year period ending on the date of purchase.

If the title was transferred to you - means - your was registered as an owner in the county office and the tax bill was issued on your name - you was clear an owner and was able to deduct interest paid on the land contract.

If the title was not transferred to you at that time - to determine if you was indeed the owner - the land contract should be analyzed - if the seller doesn't have a choice to cancel the sale - you are considered an owner.

According to your information you did own the home starting back to 2003 - and it seem as you do not qualify.

Sorry if you expected a different answer.

The main question in your situation - when did you become the owner of the property.

It is impossible for me to determine without reading your land contract.

I suggest to visit a tax professional in your area and bring your land contract with you.

See for instance - http://www.irs.gov/newsroom/article/0,,id=206291,00.html

Q. Can a taxpayer claim the first-time homebuyer credit if the purchase is pursuant to a seller financing arrangement (for example, a contract for deed, installment land sale contract, or long-term land contract), and the seller retains legal title to secure the taxpayer's payment obligations?

A. If the taxpayer obtains the "benefits and burdens" of ownership of a residence in a seller financing arrangement, then the taxpayer can claim the credit even though the seller retains legal title. Factors that indicate that a taxpayer has the benefits and burdens of ownership include:

1. the right of possession,

2. the right to obtain legal title upon full payment of the purchase price,

3. the right to construct improvements,

4. the obligation to pay property taxes,

5. the risk of loss, 6. the responsibility to insure the property and

7. the duty to maintain the property. (New 7/2/09)

So - if you obtained the "benefits and burdens" of ownership of a residence back in 2003 - you are not eligible for the credit.

However if you obtained the "benefits and burdens" of ownership of a residence after April 8, 2008 - you might be eligible for a credit.

But if you deducted interest paid - that means you used the "benefits and burdens" of ownership - and claiming a first time home buyer's credit would be most likely questioned by the IRS.