Single entry bookkeeping involves recording a transaction once. For example, if a business’s records involved just recording cash coming in and going out of the company in a cash book, that would be single entry bookkeeping.
The Advantages of Single Entry Bookkeeping are that it’s simple to understand. It’s quite intuitive to record transactions in that way, especially if you are a non-accountant.
The Disadvantages of Single Entry Bookkeeping are that it is hard to tell how much was spent on a particular expense (eg. travelling expenses) – although having analysis columns in the cash book will get round that to a certain extent. But what if you have balances brought forward from the previous year (eg. you have an outstanding invoice payment due from a customer at the start of the year) or amounts to be carried forward to the next year.