If electricity is used in December but paid for in January, which month should recognise the expense?

December.

Under accrual accounting, expenses are recognised when they are incurred, not when the bank account changes.

When the expense is incurred:

Dr Expense
Cr Accrued Payable

When payment is eventually made:

Dr Payable
Cr Bank

The simple rule is:

Use first, recognise the expense first. Pay later, settle the liability later.

Accounting is not based on when the money is paid. It is based on when the obligation arises.

权责发生制：费用应该计入哪一个月份？

12 月使用的电费，1 月才付款——费用到底应该算在哪一个月？

答案是：12 月。

在权责发生制下，费用是在实际发生时确认，而不是等到银行账户发生现金变动时才确认。

当费用已经发生时：

借：费用
贷：应计费用／应付款

当企业之后实际付款时：

借：应付款
贷：银行存款

记住一个简单原则：

先使用，就先确认费用；迟些付款，就迟些清偿负债。

会计不是看“几时给钱”，而是看“几时产生了这笔应付的责任”。