How do I write-of a ST-124 certificate of capital improvement expense on my TAX RETURN

You don't ... a capital improvements on a personal residence is added to the cost basis.  There is nothing to deduct on an income tax return. 

So, I have to wait to sell the house ?

so i have to wait until I sell the house for it to be useful ?

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@joblak1 wrote:

so i have to wait until I sell the house for it to be useful ?

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For it to be useful for reducing your tax, yes, the improvement only reduces your tax when you sell the house.

A ST-124 certificate of capital improvement expense is for an exemption from paying NY state sales tax on the building materials.  It has nothing to do with your fedearl or state income tax returns.

As others have said, all you do is add the project cost to your cost basis for any future sale. 

Are you using part of your house for a Home Office or for your business?   You can use the total of the house purchase plus the improvement to depreciate part of it.  

Yes, I have a home office. How would I do this?

Where to Report:https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-credits-deductions/take-home-office-deduction/L8nsQkp1O_US_en_US?uid=lby7fh5k