Why did my profit drop this month? How to find the cause in Xero

Short answer: a fall in profit always comes from one or more of three places: you sold less, you kept less of each sale (gross margin fell), or your overheads went up. Open the Profit and Loss in Xero for this month with last month beside it, work out how much of the drop each of the three explains, then click into the one or two lines that moved most. Before you act on it, check the drop is real: an unreconciled bank account, a bill in the wrong month or an annual cost booked all at once can make a normal month look bad. Fifteen minutes is usually enough to know which it is.

Menu names move between Xero releases and differ slightly by region. If a label below does not match your screen, search Xero Central for the report name.

First, check the drop is real

Half the “bad months” owners worry about are bookkeeping, not business. Rule these out first:

1. The bank accounts are reconciled to the end of the month. Uncoded spending and duplicates go straight into profit. If the balance in Xero and the statement balance differ, sort that out first with the bank balance guide.
2. Bills and invoices are in the right month. A supplier bill dated the 1st that belongs to the previous month, or last month’s invoices raised late, moves profit from one month to the other. Neither month is right. For work done last month whose bill has not arrived yet, an accrual in Xero puts the cost back where it belongs.
3. An annual or quarterly cost landed in one month. Insurance, software renewals, accountancy fees and some taxes are often paid once a year and expensed the day they are paid. That month looks worse and the next eleven look better. Your accountant may spread them over the year (prepayments in Xero shows how); either way, know that it happened.
4. You are reading the basis you think you are. On cash basis, profit follows money in and out of the bank, so a customer paying late moves sales into next month. On accrual basis it follows invoices and bills. Mixing the two up explains a lot of surprises; see the cash vs accrual guide.
5. An exchange rate moved. If you invoice, buy or bank in a foreign currency, Xero revalues the open amounts at the report date, and Unrealised Currency Gains or Bank Revaluations can swing profit with no change in trading. A gain last month that reverses this month looks like a drop. Take those lines out before comparing (unrealised currency gains in Xero).

If all five check out, the drop is real. Now split it.

The three causes, and how to size each one

Take this month and last month from the Profit and Loss, and work out three numbers. Together they add up to the whole change in profit.

Cause	How to work it out	What it tells you
Sold less	Change in sales × last month’s gross margin %	Profit lost because there was less to sell, at the margin you were already making
Kept less of each sale	This month’s sales × (this month’s margin % − last month’s margin %)	Profit lost because direct costs rose faster than sales: supplier prices, discounts, wastage, the job mix (profit by job)
Spent more on overheads	Change in total operating expenses	Rent, wages (as a % of sales), software, marketing and everything else below gross profit

Gross margin is gross profit divided by sales. If your Profit and Loss has no cost of sales section, the second line is zero and everything is either sales or overheads. The gross profit margin guide covers how Xero works it out and why the cost of sales section matters.

The biggest of the three is where to spend your time. A drop that is mostly “sold less” is a sales or seasonality question. One that is mostly “kept less” is a pricing or cost question. One that is mostly overheads usually comes down to one or two lines you can name.

How to do it in Xero, step by step

1. Run the Profit and Loss for the month that worried you (Reports, then Profit and Loss). Under Compare with, add 1 previous period. Run it a second time comparing with the same month last year, so a seasonal dip does not look like a problem.
2. Read three totals in each column: total sales (trading income), gross profit and total operating expenses. Work out the three numbers from the table above.
3. Find the lines that moved. Scan for the largest change in each section. Usually one or two lines explain most of the drop.
4. Click the amount on a line that moved. Xero opens the transactions behind it (the Account Transactions report). Look for anything large, anything that looks like an annual bill, anything duplicated and anything in the wrong month. Profit and Loss detail in Xero shows how to pull every line’s transactions at once, with a worked example.
5. For a fall in sales, look by customer. The Income by Contact report (or Sales by customer, depending on your version) shows whether sales fell across the board or because one or two customers bought less. The Xero sales report guide shows how to run it by customer and why its total is often below the Profit and Loss.
6. Write down one sentence per cause. “Sales were down $3,500, mostly one customer’s order moving to October” is the kind of note that makes next month’s decision easy.

A worked example: a $6,700 fall

An events caterer’s net profit dropped from $8,800 in August to $2,100 in September. Here are the two columns of the Profit and Loss:

	August	September	Change
Sales	$62,000	$58,500	−$3,500
Food and drink purchases	$19,800	$20,900	+$1,100
Casual event staff	$5,000	$5,400	+$400
Gross profit	$37,200 (60%)	$32,200 (55%)	−$5,000
Operating expenses	$28,400	$30,100	+$1,700
Net profit	$8,800	$2,100	−$6,700

The checks: the bank accounts were reconciled, and the bills were in the right month. Operating expenses include a $1,450 annual insurance renewal, paid and expensed in September. That is real, but it is a once-a-year cost.

Splitting the $6,700:

• Sold less: sales fell $3,500. At August’s 60% margin, that cost $2,100 of profit.
• Kept less of each sale: at August’s margin, September’s $58,500 of sales would have made $35,100 of gross profit. It made $32,200, so the thinner margin cost $2,900.
• Overheads up: $1,700, of which $1,450 is the insurance renewal and $250 is small changes across several lines.

$2,100 + $2,900 + $1,700 = $6,700. The biggest single cause is the margin, not the lower sales the owner had been worrying about. Clicking into food and drink purchases showed a supplier price rise in early September, and two large events had been quoted in July at the old prices. Food costs went from 32% of sales to 36%. (Showing every line as a share of sales like this is a common size P&L; that guide works through a whole year this way. To check for this every month before it costs a quarter’s profit, see the P&L management routine.)

What the owner does next: updates the menu pricing for new quotes (the price increase calculator shows how much volume a price rise can lose before profit falls), and notes that the insurance is a one-off. Without the insurance, September’s profit would have been about $3,550: still down, but by $5,250, not $6,700.

What to do about each cause

• Sold less. Compare with the same month last year before you worry; many businesses are seasonal. If it is one customer, call them, and check how much of your sales they are with the customer concentration calculator. If it is broad, the break-even calculator shows how far sales can fall before you stop covering your costs.
• Kept less of each sale. Check supplier prices, discounts and quotes made at old prices. The margin and markup calculator turns a target margin into the price you need to charge.
• Spent more on overheads. Name the line. If it is a one-off, note it and move on. If it is new and recurring (a new hire, a new subscription), it raises your break-even point every month from now on. Before the next hire, the can I afford to hire calculator shows the extra sales a role has to bring in. For a full review of where the money goes over a year, see where is my money going?

If profit is fine but the bank is not, that is a different question with different causes: see profit but no cash. For a monthly check of the whole picture (profit, margin, free cash, customers and bills), see how do I know if my business is doing well?

Common questions

Should I compare with last month or the same month last year? Both. Last month shows what just changed; the same month last year takes out seasonality. A drop that shows up against both is the one to act on.

One month dropped, but the quarter looks fine. Should I worry? Usually not. Single months are noisy: big jobs, timing of bills and annual costs move profit between months. Look at a rolling three months, or the trend over a year, before you change anything.

Why did my profit drop when sales went up? Either the margin fell (you sold more, but kept less of each sale: discounting, higher supplier prices, or more of your lower-margin work) or overheads rose by more than the extra gross profit. The same three-way split shows which.

Can I see profit by month for the whole year in Xero? Yes. Run the Profit and Loss for one month and compare with the previous 11 periods. It is the quickest way to tell a one-off from a trend; the Profit and Loss by month guide shows how to read the twelve columns. A budget vs actual report adds what you expected each month.

Knowing what changed every Monday

ReportPilot reads your Xero figures and does this check for you in a short plain-English email every Monday. It says how net profit moved against the month before and, when a single line drove a large share of the change, names that line. It flags gross margin when it moves by 3 percentage points or more, and any expense line running more than 25% above its six-month average by a meaningful amount, so a supplier price rise or an annual bill is pointed out instead of found by accident. It also covers cash, who owes you and bills due soon. It asks Xero for read-only access, and there is a 14-day free trial with no card.