Short answer: Every transaction gets categorized, every account gets reconciled against the actual statement, and you get a profit and loss and a balance sheet you can hand to a lender or an accountant without apologizing for them.
Here is the month, in order.
Transactions come in from your bank and credit-card feeds and each one gets assigned to the right account. This sounds mechanical and mostly is, until it isn’t: a transfer between your own accounts is not income, a loan deposit is not revenue, an owner draw is not an expense. Getting these wrong is the most common reason a P&L looks fine and is not.
Then every account gets reconciled. Reconciling means the ending balance in the books matches the ending balance on the statement, to the penny, with every difference explained. This is the step that catches missing transactions, duplicates, and bank errors. A book that has not been reconciled has not really been kept — it has only been typed.
Anything unclear gets sent to you as a short list rather than a running stream of questions. You answer once.
Then the month closes and the reports come out: a profit and loss showing what you earned and spent, and a balance sheet showing what you own and owe. If payroll runs through us, the payroll filings go out on their own schedule alongside this.
What should never happen is a surprise at tax time. The point of a monthly close is that December is a normal month, not an archaeology project. By the time your return is prepared, the numbers have already been right for eleven months.
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