Josh McCullough, do you invoice the tenant or send him a BILL?

I don't chase rent and I don't work with tenants.I do send monthly rental invoices from Quickbooks. 

the safe harbor applies to amounts paid during the tax year to acquire or produce what the regs call a “unit of property” (UOP), you must meet these requirements: (1)you need to have written accounting procedures treating as an expense for non-tax purposes amounts paid for property costing less than a specified dollar amount (which will be 2500 for you), or with an economic useful life of 12 months or less;.(2) the taxpayer treats the amount paid for the property as an expense on its books and records in accordance with its accounting procedures. ( do this on your bookkeeping software or whatever you utilize)(3) the amount paid for the UOP doesn't exceed $2,500. as substantiated by the invoiceNote: The cost for the Unit of Property includes l additional costs (for example, delivery fees, installation services, or similar costs) if these additional costs are included on the same invoice with the property. 2) Small taxpayer safe harbor: To be eligible for the safe harbor, the total amount of improvements for the property for the tax year may not exceed the lesser of $10,000 or  2% of the property's unadjusted basis. 

If you feel you must give your business info for a better deal, it would be best for you to pay from a personal account, ensure you have records of specifically what materials were needed for the personal project and receipts or invoices that listed those items.

The 2nd best proof would be an invoice or a receipt signed by your friend.

Copies of these records must be provided within 30 days of completing the renovation or issuing the final invoice.

Since my late fees are automatically added to their invoices (I have a recurring late fee set up), most of them pay on time to avoid high late charges.

@Scott Carder  we hit a happy medium.. get invoice on the 1st pay on the 10th  get invoice on the 7th we pay on the 10th of the next month.. teaches our subs to get the billing in time.Now to be fair we are using bank loans.. so they send an inspector out before we can get our draw so we need our draw request to them by the 2nd to get our draw by the 10th.. so if our subs want to get paid they get us the invoice.. plus they need to sign lien release with check.

After the back fill on the foundation was complete I got the invoice from my excavator and fell down.

Or the other developer that had an outstanding invoice of 50k that he decided he didn't want to pay right now because his property hasn't produced any income, but how happy he would be to loan me a $1000 at 15% if that would help.