If you sent a payment early for a bill that is an expense to you in January, then it's not an expense until January, whether on a accrual or cash basis. It's like a prepayment or deposit on account. Not an expense, but an asset until it is used. That's the accounting view.
However, that's not how 1099 reporting works. Instead, it's based on the payments you made to the recipient, regardless of whether or not they earned the payments in the tax year.
The two don't have to agree. It's not important to make your business expenses match the cash payments to your vendors for the different tax reporting, if for no other reason that not all payments to vendors are allowable business tax deductions/expenses. But also because the different types of reporting are asking for different things.
