Big events — weddings, home renovations, holidays, a new baby, a milestone birthday party — all share one common trait. They cost more than you expect. Not sometimes. Almost always.
This isn't bad luck and it isn't poor planning. It's the nature of complex one-off projects where you can't fully know the scope until you're in the middle of them. The good news is that knowing this in advance changes everything.
Build your contingency in from the start
Before you do anything else: whatever your estimated total budget is, add 15–20% to it and treat that as the real number you need to save. This is your contingency, and it should be non-negotiable.
For home renovations specifically, 20% is the commonly cited industry figure for a reason. Behind walls and floors are things no survey fully reveals. Tradespeople are delayed by suppliers, rescheduled by other jobs, or discover complications mid-job. A budget without contingency isn't a real budget — it's an optimistic estimate.
For weddings, supplier price increases between booking and the day, last-minute guest additions, and the small costs that nobody thinks to include (thank-you cards, tips, transport, hair touch-ups) routinely add 10–15% to what people initially planned.
The contingency doesn't guarantee you'll need it. But if you do need it and haven't got it, you'll be funding the difference on a credit card.
Work backwards from the date
Once you have a total in mind, the question becomes: how do I get there?
Take your total budget and divide it by the number of months between now and when you need the money. That's your monthly savings target.
For example: a holiday costing £2,400 in nine months means saving £267 a month. A £10,000 home renovation in 18 months means saving £556 a month. If those numbers aren't achievable on your current income, you know immediately — and you have time to adjust (a later date, a smaller scope, additional income) rather than discovering the shortfall three weeks before you start.
Keep the project budget separate from your living expenses
Big events are where budgeting often breaks down because costs get merged with everyday spending. You buy something for the wedding and charge it to your regular account. You pay a deposit from your current account. After a few months you've genuinely lost track of how much you've spent.
Using a dedicated savings account or clearly tracking every project-related cost separately makes a significant difference. You can see your running total, you have a clear picture of what's committed versus what's spent, and you don't accidentally spend your holiday money on a water bill.
Get every cost on the list — including the boring ones
For any big event, the costs you forget are often the ones that sting most, because they arrive unexpectedly late in the process. A few categories people commonly miss:
- Weddings: Cake cutting fee at the venue, card box and stationery, tips for suppliers, wedding night hotel, dress alterations, end-of-night transport
- Home renovations: Permits and planning fees where required, skip hire, redecoration after structural work, temporary living arrangements if needed, replacing furnishings that don't fit the finished room
- Holidays: Travel insurance, airport parking or transfers, visa fees, baggage charges, spending money beyond accommodation and flights
- New baby: The immediate kit (pram, cot, car seat) gets planned for; the ongoing costs in the first year (nappies, formula if not breastfeeding, clothing every few months) often get underestimated
Prioritise ruthlessly within your budget
What are the things that genuinely matter to you about this event? For a wedding, for most couples, it's the food, the photography, and the people. Everything else is a nice-to-have. For a renovation, it's the quality of the work in the rooms you use every day. For a holiday, it's the things you'll actually remember.
Once you've decided what matters most, the rest of the budget becomes a negotiation with yourself. Spend generously on the things that count, and find savings on the things that don't.
One last thing: avoid funding it with credit if you can
Not everyone can save the full cost upfront — sometimes that's not realistic. But as a principle: if you borrow to fund an event, the event isn't over when it ends. You're still paying for it months or years later, with interest. That colours the memory of it more than people usually acknowledge beforehand.
If borrowing is unavoidable, have a specific repayment plan in place before you commit to the expense, not after.
Try the project budget planner
List every estimated cost, track what you've actually spent, and see the gap between the two at a glance. Useful for anything with a fixed scope and a deadline.
Open Project Budget