According to the SBA on Page 4 of the information available at: https://home.treasury.gov/system/files/136/PPP–IFR–Revisions-to-Loan-Forgiveness-Interim-Final-Rule-and-SBA-Loan-Review-Procedures-Interim-Final-Rule.pdf:

A nonpayroll cost is eligible for forgiveness if it was:

  1. Paid during the covered period; or
  2. incurred during the covered period and paid on or before the next regular billing date, even if the billing date is after the covered period.

 Example: A borrower that received a loan before June 5, 2020 uses a 24-week covered period that begins on June 1 and ends on November 15. The borrower pays its electricity bills for June through October during the covered period and pays its November electricity bill on December 10, which is the next regular billing date. The borrower may seek loan forgiveness for its June through October electricity bills, because they were paid during the covered period. In addition, the borrower may seek loan forgiveness for the portion of its November electricity bill through November 15 (the end of the covered period), because it was incurred during the covered period and paid on the next regular billing date.