Every transaction shows up in two places: the P&L and the balance sheet. Once you can see how something lands on both, the accounts stop being a mystery.
Quick reminder. The P&L is a film: income and costs over a period, ending in profit. The balance sheet is a photo: what you own and owe at a single moment.
Let's follow a single retainer across three months and watch both statements move.
Month 1: the client pays £30,000 upfront for three months of work.
Cash goes up £30,000. But you've earned nothing yet, so the P&L shows no revenue; the £30,000 sits as deferred revenue on the balance sheet.
Month 2: you deliver a third of the work.
Now £10,000 moves onto the P&L as earned revenue, and the deferred liability drops to £20,000.
Month 3: you deliver the next third, and pay a £5,000 supplier on credit.
Another £10,000 of revenue, deferred falls again, and the supplier cost hits the P&L while the unpaid bill sits as accounts payable until you pay it.
See what happened? Cash arrived in month 1. Revenue arrived in months 2 and 3. Costs and cash moved on different days again. The two statements tell the same story from different angles, and only together do they tell the truth.
When you look at your accounts, read them as a pair. The P&L tells you if the work made sense. The balance sheet tells you what's still owed, owing, and unearned underneath it.