Wave

Wave does invoices, receipts and double-entry bookkeeping for free, and earns on card payments and on a paid tier that automates the parts you would otherwise do by hand. For a sole trader sending a dozen invoices a year it is the cheapest honest answer. Payroll and the advisor service exist in some countries only, which is worth checking before a whole tax year lives in it.

Starter is free and covers invoicing and bookkeeping. Pro is $19 a month or $190 a year and adds automation, receipt scanning and the waived per-transaction fee on Pro's first ten card payments each month. Wave Advisors, the service with actual bookkeepers in it, starts at $149 a month. Card processing is charged on both plans at 2.9 percent plus 60 cents, and 3.4 percent for Amex.

Sole traders and one-person companies invoicing a handful of clients who want the books tidy without paying monthly for the privilege. Payroll, stock or a bookkeeper of your own is the point at which the tools built for that are worth their price.