@fvhelms wrote:
I have receipts for all purchases, and invoices from various locations. Is that all I need....
That is essentially all you need; it is per invoice or per item as substantiated by the invoice.
See Treas. Reg. §1.263(a)-1(f)(1)(ii)(D)
See also https://www.irs.gov/businesses/small-businesses-self-employed/tangible-property-final-regulations
