Can capital loss on a property that is overseas be used to offset capital gains? Are these special rules for capital gains/losses of overseas assets?

[nab2]

I have a house overseas which will sell for a substantial loss and I want to use those losses to offset gains on assets within the USA.

[Carl]

You need to provide more details. Is/was the house used for business purposes of any type during any period of time that you owned it? For example, was it a rental property, or did you ever claim a home office in this property?

Typically, losses on the sale of personal property, regardless of it's location on the planet, are not deductible.

[nab2]

It was used as a primary residence several years ago and is now empty/a vacation home that is hardly used.

[Carl]

Any losses on the sale would not be deductible, and that has nothing to do with where the property is located. Losses on the sale of personal property are just not deductible from your other income.

[nab2]

Thanks, so since an investment property can be used as a capital loss, that raises the question: What are the IRS rules for reclassifying a house which was formerly a residence as an investment property?

[Carl]

The house was not used in any way for the production of income, and based on your statement earlier of it being your primary residence before, it's quite clear it was not purchased for investment purposes either. Understand that while others may help you claim it as such, should you ever be audited on it you can expect to have a difficult time proving otherwise.

[Hal_Al]

By your own description ("It was used as a primary residence several years ago and is now empty/a vacation home that is hardly used"), you clearly have personal use property (and a loss cannot be claimed), not investment property. 

Had you rented it out for the last "several years", you could claim a partial loss (prorated for for business/rental use time).