Technically speaking, you don't have to have the invoice or receipt to take the deduction.HOWEVER,In the event of an audit, anything that you don't have an invoice or receipt for (credit card statements don't count) will likely be disallowed by the auditor, effectively making it non deductible.Online storage space is cheap. 

If not, you should get one.EDIT - Found this on the county website.The Horry County Auditor's Office is responsible for the collection and processing of Personal Property Returns (Form PT-100).

That is what you called an inexperienced staff auditor!

Do the same for the treasurer and the auditor.  

Auditors take the same approach, is it going to be worth the effort to continue an audit, is there fraud, violations of law.......the hunt has to be worth the benefits of the kill. :) 

I would do a search on the county auditor site.

I always use "Butler County Auditor" site for searches, you can run reports off of there that will show you delinquent tax homes. 

Instead, an auditor might look at (A) address on your driver's license or other docs, (B) utility bills compared with rental logs, (C) where you get your mail, etc.  

However if you're doing this year after year and just claiming oh it's intent was rental you're an auditor's dream basically. 

I am a certified building performance institute quality control inspector and energy auditor.