Budgeting with irregular income requires one key adjustment: always plan from your lowest realistic monthly income — not your average — and direct any surplus above that floor into a buffer fund rather than spending it.
The fundamental rule: budget from your floor, not your ceiling
Always budget from your lowest realistic monthly income, not your average or your best months. If your income over the last 12 months ranged from £800 to £2,000, budget from £800. In better months, the surplus goes to a buffer fund rather than lifestyle spending.
Building an income buffer
An income buffer is different from an emergency fund. An emergency fund covers unexpected events. An income buffer covers expected variability — the fact that some months are just lower than others. Target one to two months of essential expenses as a buffer. Draw from it in lean months, rebuild in strong ones.
A worked example
Monthly income over six months: £1,800, £600, £2,200, £800, £1,500, £1,100. Floor: £600. Budget from £600 means fixed essentials must cost less than £600. In the £2,200 month: cover £600 essentials, add £400 to income buffer, set aside £400 for tax, £800 remaining. In the £600 month: essentials covered exactly from income.
Tax set-aside: the non-negotiable
If you are self-employed, set aside 20-25% of every payment for tax immediately. Keep it in a separate account and treat it as untouchable. The most common financial crisis for self-employed people is a large unexpected tax bill that was actually completely predictable.
- Open a dedicated tax savings account on the day you register as self-employed
- Set aside 20-25% of every payment automatically
- Do not touch this money for anything except tax
- Review your set-aside rate each January once you know the previous year's actual bill
General guidance only — not regulated financial advice.