The second income that is not worth the hours

The points below about side income are ordered by how much difference they make, not by how often they get repeated.

Count the unbilled hours

Admin, invoicing, chasing payment, marketing and unpaid preparation are all part of the time cost. Dividing net income by total hours including these often halves the apparent rate. Comparing that honest figure to overtime or to a better-paid main job frequently changes the decision.

Start-up costs belong in the same sum, since equipment, insurance, a website and a first year of registration are all paid before any of the work is, and they can absorb most of a first year of income.

Tax applies at your marginal rate

Additional income is stacked on top of your main earnings and taxed at your highest band. For a higher-rate taxpayer this can remove a large fraction of what feels like extra money.

The net figure is what should be compared to the hours given up. Extra income can also reduce means-tested support or take a household past a threshold at which an allowance is withdrawn, so within certain bands the effective rate is far above the headline one.

Obligations start early

Registration, record-keeping and filing obligations typically begin at modest income thresholds. Ignoring them is a common and avoidable problem, and thresholds vary by jurisdiction. Setting aside a proportion of every payment for tax from the first invoice prevents the classic year-two shock.

For most people, read the employment contract as well, since clauses requiring disclosure of outside work, or prohibiting work for a competitor, are common and are frequently enforceable even where the side work is small.

Some side income buys optionality

Work that builds a skill, a portfolio or a client base can be worth doing below its apparent hourly rate. Work that simply exchanges hours for money at a poor rate rarely is.

Distinguishing between the two before committing is the useful discipline. Optionality has a shelf life, so work taken on to build a portfolio is worth reviewing against a date, by which point it is either producing better-paid work or it has become cheap labour.

The cost is usually rest

Second incomes are generally funded from evenings, weekends and recovery time. That cost lands on health, relationships and performance in the main job, none of which appear in the calculation.

Put simply, a temporary push for a specific goal is different from an indefinite arrangement. Where a second income is covering essentials rather than funding a goal, calling it a choice misdescribes it, and the checks worth making are entitlements, the rate for the main job, and whether any of the debt behind it can be restructured.

The version that works better than more hours

Raising the rate on work you already do usually beats finding more of it, because the hours are committed either way and the admin does not increase. Repeat clients cost far less to serve than new ones, and a rate that only rises for new clients leaves the largest share of the work sitting at the oldest price. Income that continues without further hours — a licence, a royalty, something sold more than once — behaves differently from selling time, though it generally takes a great deal of unpaid time to build in the first place.

Once a side income becomes substantial the tax, insurance and structure questions change with it, and one session with an accountant at that point costs less than a year of getting it slightly wrong.

Everything above, in order of what to do first

1. Count the unbilled hours. Admin, invoicing, chasing payment, marketing and unpaid preparation are all part of the time cost.
2. Tax applies at your marginal rate. Additional income is stacked on top of your main earnings and taxed at your highest band.
3. Obligations start early. Registration, record-keeping and filing obligations typically begin at modest income thresholds.
4. Some side income buys optionality. Work that builds a skill, a portfolio or a client base can be worth doing below its apparent hourly rate.
5. The cost is usually rest. Second incomes are generally funded from evenings, weekends and recovery time.
6. The version that works better than more hours. Raising the rate on work you already do usually beats finding more of it, because the hours are committed either way and the admin does not increase.

The takeaway

Divide net income by total hours including admin. Then decide if it clears the bar.

Pick the one that costs you least, and let the rest wait.