Twelve months or twenty-four?

A bank statement programme will usually let you choose between twelve and twenty-four months of deposits. Most people send whatever their bank exported first. That is a decision, made badly.

Twelve months helps a business that grew

If this year is meaningfully better than last year, twenty-four months drags the average backwards by including months you have outgrown. Twelve months lets the current shape of the business speak.

Twenty-four months helps a business that wobbled

One quiet quarter inside twelve months costs you a quarter of your average. Inside twenty-four it costs you an eighth. If your work is seasonal, or a contract ended and another started, the longer window is usually kinder.

The right answer is whichever produces the larger honest number. Both are honest. Only one is larger.

The case where it is not close

A one-off windfall — a catering contract, a settlement, an unusual licensing cheque — inside a twelve-month window can inflate the average so obviously that an underwriter discounts it. Twenty-four months absorbs it into something believable. Believable beats large.