Building a 12-Month Cash-Flow Forecast

Part B: Understand the Money

A forecast is a plan with numbers in it. It will be wrong in places, and that is fine. What it does is turn a vague worry, “I think money is tight in the spring,” into something specific: “In March I will be about $4,000 short unless something changes.” You can act on the second sentence.

The whole thing rests on one distinction that trips up a lot of owners. Sales are when you earn money. Cash is when it lands in your account. A forecast tracks the second one. If you invoice in January and the customer pays in March, that money belongs to March.

The four lines, one month at a time

Every month in your forecast has the same four lines, and each month’s ending cash becomes the next month’s opening cash. That chain is what makes a forecast powerful: one month’s shortfall shows up as the next month’s problem.

Opening cash. What is in the bank at the start of the month. For your first month, look at your actual balance. Use your bank account, not your accounting software’s idea of it.

Cash in. Money you expect to actually receive that month. Go through your open invoices and ask, when will each realistically be paid, based on how this customer behaves? Then add sales you expect to make and collect within the month, such as card payments and deposits. If a customer usually pays 45 days after the invoice, put it in the month 45 days out.

Cash out. Everything you will actually pay: materials, payroll, rent, insurance, vehicles, software, advertising, and the bigger irregular bills such as an annual insurance premium or a piece of equipment. Put each in the month it will leave your account, not the month it relates to. Include your own pay too, a topic we come back to in Owner Pay Versus Business Money.

Ending cash. Opening cash plus cash in, minus cash out.

Here is a labelled hypothetical for a small service business. In January it opens with $8,000, collects $14,000 and pays out $16,000, so it ends at $6,000. February opens at $6,000, collects $9,000, pays out $12,000, and ends at $3,000. March opens at $3,000, collects $20,000, pays out $13,000, and ends at $10,000. On paper the business looks fine by March. But look at February: cash fell to $3,000, and a single late customer could push it below zero. Without the forecast, February would have been a surprise.

How to build yours

Start with a blank grid: twelve columns for the months, and rows for the four lines, with cash in and cash out broken into categories. The free 12-Month Cash-Flow Forecast on the Resources page has this laid out for you, but a paper grid works just as well.

Then work through it in this order. Fill in opening cash for month one. Enter your known bills for all twelve months, since rent, payroll and subscriptions are the easy part. Add the irregular bills in the months they land. Then, and only then, estimate cash in, starting with invoices already sent and moving on to work you expect to win. Calculate ending cash for each month and carry it forward as the next opening cash.

The result is a row of ending balances. Find the lowest one. That is the number the whole exercise is for, because it tells you how much cushion you need and when you will need it.

Be conservative where it counts

Owners lean optimistic about money coming in and forgetful about money going out. Counter that on purpose. Collect later than you hope: if a customer promised 30 days, plan for 45. Count only work that is signed or genuinely likely, not every lead you have spoken to. Leave out the hoped-for big job unless it has a deposit behind it. And round costs up, not down.

Keep in mind the mirror image: a conservative forecast that shows a tight month is good news. You found it while you could still do something. You can move a purchase, ask for a deposit, chase an invoice or trim spending. You cannot do any of that on the day the payroll bounces.

Then keep it alive. At the end of each month, replace the forecast with what actually happened, and slide the forecast forward one more month so it always looks twelve months ahead. Over time you will learn how your own customers really pay, which is worth more than any template. For why timing matters so much, see Working Capital and the Cash-Conversion Cycle.

Open a grid and fill in three things today: your actual bank balance as opening cash, every bill you already know about for the next twelve months, and every unpaid invoice with the month you honestly expect it to be paid. Leave future sales for later. Those three pieces alone will show you the shape of the next few months.

Expect two to four hours for the first version, most of it gathering invoices and bills, then about 30 to 45 minutes a month to update it. It costs nothing with the free spreadsheet or a pen and paper. The hard part is looking honestly at what you collect and when. The math is easy.