[dsimms]

I agree: it catches entry errors, which is really handy in a system where you're hand-writing them twice.

But if you're writing a computer system that's simply duplicating one entry from a human in two places in data store, is that "double entry"? is it useful?

But the idea that you would want to reconcile one view with another independently reported one is super useful. (Almost every financial-oriented company builds a system like that, I would bet.)

[HeavenFox]

I once used Mint, which is single entry. One day I logged into my account and noticed my net worth is a bit off. Looking at my monthly expense and income, I didn't see anything out of ordinary, so I just shrugged it off.

A couple of months later I finally realized I opened new savings account to take advantage of a promotion and forgot about it. The opening deposit was deducted from my checking account. Since it's classified as a "Transfer" it doesn't show up in expenses. I linked the account, and now I am a few thousand dollars richer than I previously thought.

This kind of mistake will never happen in a double entry accounting system.

It was then I began migrating my personal accounting to a double entry system I developed myself. Hopefully I can make it available to the public soon :)

[pbourke]

"debits and credits balance" is a very useful constraint to have in your system in order to maintain data integrity. Transactions can also get quite complex - think of a salaried payroll deposit - this is a transaction with 5-10 splits from various accounts. Even a typical ecommerce sale might have 4-5 when you include commissions owed, shipping, sales tax, etc.