Initially I started to keep my accounts on an Excel spreadsheet, but very quickly migrated to an open source package GNUcash (  This is free and has some limitations but provides better functionality than a spreadsheet.  It is easy to produce an income statement and balance sheet each month and “drill down” to see the individual transactions behind the account totals.  Recurring postings can be set for items such as depreciation and bank accounts can be reconciled to bank statements by ticking off the transactions.

For more sophisticated business models, or for business with higher transaction volumes, it is likely to be worthwhile investing in a paid-for accounting system.  There are a number of cloud based packages which bring other advantages.