Added garage converted old garage to home office space - deduct as home office or whole house

[missimc]

This past summer I had a new 2-stall attached garage built -  the old attached one stall garage I had converted to home office space: doors had to be put in, tuckpointed, electrical and stairs - do I claim this under entire home or office renovations?

[Bsch4477]

Your new garage is a capital improvement which increases your home cost basis. 

[missimc]

That wasn't my question - I know my new garage will be a whole home improvement... the question is what do I consider my old garage renovated to new home office - home improvement or office improvement with the extensived work - the old attached one stall garage I had converted to home office space: doors had to be put in, tuckpointed, electrical and stairs - do I claim this under entire home or office renovations?

[Carl]

Whichever is better for you.

The renovation adds to the cost basis of the entire house. If the new HO is say, 10% of your total floorspace and claiming 10% of that floorspace based on the new higher cost basis is better, go that way.

Or you can claim the HO based on the cost basis before the renovations at say, 10% of the floor space. Then add the renovations at their cost and 100% business use.