accounting for undocumented contracters

[Mario F.]

Hello, I submitted an offer on a condo that needs a lot of work done. One of the maintenance workers in the complex offered to do some repairs and improvements for me but I don't think he has documents. Might be cash payments, etc.  So how do you account for this kind of work if payment is in cash?  I'd like to make sure I get the proper tax write off for any repairs. 

Thanks!

mario