Yes it is a change in accounting principle. And a rather drastic change. Accrual Basis of accounting is the most fundamental accounting assumption which is regarded throughout the world. Thus if a person either departs or adopts the accrual basis its a change in accounting principle.

Gary L. Sundem has written:

'The Accounting Education Change Commission' -- subject- s -: Accounting, Accounting Education Change Commission - Tempe, Ariz. -, Study and teaching

Change in accounting estimate. The switch from double-declining balance method to straight-line method should be treated as a change in accounting estimate and accounted for prospectively. This change should not be applied retroactively.

It is important to change the accounting period when using Peachtree Accounting Software because accounting periods are units of time that divide your fiscal year for reporting purposes and therefore it is paramount to change this at the end of each period to move to the next.

However, if this is not changed, the Peachtree software automatically assumes the default date to be the Peachtree system date and adopts this.

the double entry system