Bookkeeping systems for solo contractors

Bookkeeping for a solo contractor is a smaller problem than the word suggests: one income stream, dozens (not thousands) of transactions a month, no payroll, no inventory. The job is keeping records that can answer four questions at any time, for seven years. Pick the lightest system that genuinely answers them and bookkeeping stops being a topic.

What the records must answer

• What did you earn? Every invoice, its date, and when it was paid.
• What did you spend? Every business expense with its receipt or supplier invoice (the taxable supply information), and the basis for any mixed-use split.
• What do the GST returns rest on? The period-by-period trail from invoices and receipts to the figures you filed.
• Can you show it later? Everything above, reachable for at least seven years. Electronic records are fine; a shoebox is technically fine too, if it can genuinely answer the first three.

System one: the spreadsheet

One sheet of invoices, one of expenses, a folder of PDFs and photographed receipts. Free, fully yours, and completely adequate for a simple year, which is why so many contractors start here. What it demands is you: every entry is manual, the tax math is whatever formulas you maintain, and the system's accuracy is exactly as good as your discipline in week forty as in week one. The failure mode isn't the spreadsheet; it's the quarter where nobody opened it.

System two: general accounting software

The full-ledger tools handle everything a small business can be: bank feeds, reconciliation, payroll, inventory, reporting. If your contracting is heading toward a company with employees, or your accountant runs your books in one, it's the natural home. What it demands is engagement with accounting itself: a subscription, some vocabulary, and features sized for businesses more complicated than a solo contractor, which is why some sole traders find themselves paying for a ledger they use three screens of.

System three: purpose-built contractor tools

The middle path: tools built around the solo contractor's actual loop (invoice, get paid, set tax aside, file) rather than the general ledger. Coffer is one of these: invoicing with the records kept automatically, NZ tax math per payment, and the set-aside tracked continuously. What this class trades away is breadth: when a business outgrows the solo shape, it graduates to the general tools, ideally exporting clean history with it.

Choosing, in one pass

• Match the system to the shape of the business, not its ambitions: a solo contractor doesn't need payroll modules because someday they might hire.
• The habit matters more than the tool: record income and expenses when they happen, on any system, and every downstream job (GST returns, the IR3, the accountant handoff) gets easy.
• Ask your accountant what they can work from if you use one; records they can ingest directly shrink the annual fee.

How Coffer helps

Coffer's bet is that most solo contractors want the third shape: the records kept as a side effect of invoicing, the tax math done per payment, and the seven-year trail (invoices, payments, expenses, tax events) accumulating without a bookkeeping session ever being scheduled. The help center shows the day-to-day.