Bookkeeping systems for solo contractors

Bookkeeping for a solo contractor is a smaller problem than the word suggests: one income stream, dozens of transactions a month rather than thousands, no payroll, and no inventory. The job is keeping records that can answer four questions at any time, for seven years. If you pick the lightest system that genuinely answers them, bookkeeping stops being something you think about.

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, and a shoebox is technically fine too, as long as it can genuinely answer the first three.

System one: the spreadsheet

One sheet of invoices, one of expenses, and a folder of PDFs and photographed receipts. It's 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 is only as accurate as your discipline, which has to hold up in week forty as well as in week one. What tends to go wrong isn't the spreadsheet itself, 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, and 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. That is why some sole traders find themselves paying for a ledger when they only use a few screens of it.

System three: purpose-built contractor tools

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

How to choose between them

• 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. If you record income and expenses when they happen, on any system, then every downstream job gets easier: the GST returns, the IR3, and the accountant handoff.
• 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 is a purpose-built contractor tool, the third system above. Your records build up as a side effect of invoicing, Coffer does the tax math on each payment, and a seven-year trail of invoices, payments, expenses, and tax events piles up without you ever scheduling a bookkeeping session. The help center shows the day-to-day.