Your Cash Forecast Is Only as Good as Last Month's Close

Most of the owners we work with care about one number more than any other, and it's the cash balance a few weeks from now. A good 13-week cash forecast answers that question, and for a $1–10M company it may be the most useful report on the shelf. Its reliability depends on the accuracy of the financial information it starts from – beginning with the balance sheet, the part that tends to get skipped. A weak close can also misstate revenue, expenses and profit, distorting the operating assumptions used to forecast future cash.

How the forecast is built

A 13-week forecast is simple in theory – you start with cash on hand, add what you expect to collect each week, subtract what you expect to pay, and see where the balance lands. Last month's close provides the starting balances, supplemented by current activity and expected sales and spending:

• Starting cash, from reconciled bank accounts
• Collections, from accounts receivable and when each customer actually pays
• Payments, from accounts payable, payroll, debt service, credit card payments due and recurring commitments, and the timing of those
• Known one-time items are added in, from contracts, tax deadlines and planned spending, such as insurance deposit premiums, capex purchases, etc.

With accurate balances and realistic operating assumptions, the forecast becomes largely a timing exercise. Without them, it can be precise about the wrong answer.

Where a weak close breaks the forecast

These are the gaps we find most often when we take over a company's books, and each can become a cash-impacting surprise:

• Bills that were never recorded. If a vendor invoice is sitting in someone's inbox, it's missing from payables, and the payment is missing from the forecast until it surfaces.
• Bill payments recorded as new expenses instead of applied to existing bills. That leaves paid bills open in AP, and the forecast may count the payments again.
• Receivables with unrealistic collection dates. Old invoices, disputed balances, or invoices with due dates that don't reflect when unfinished work will be completed can overstate or accelerate expected collections.
• Customer deposits booked as revenue. The cash is already in the bank and the work is still ahead of you. If those remaining costs aren't included, the forecast overstates available cash.
• Payroll taxes and benefits withheld and employer contributions owed but not remitted. That cash looks available right up until the deposit deadline.
• Sales tax collected and not yet paid. Same problem, with penalties attached if it's late.
• Credit cards that haven't been reconciled. Unrecorded charges can make the upcoming payment larger than the forecast shows.

At KTI, invoices were being issued early for work that wasn't complete, so receivables "were appearing on the books despite not yet being truly due and payable." The company looked stronger on paper than it was in the bank, and that gap put a credit line at risk until the billing process and reporting were rebuilt.

The margin for error is thin

JPMorgan Chase Institute research on nearly 600,000 small businesses found that the median business holds enough cash to cover 27 days of typical outflows, and a quarter of them hold fewer than 13. Labor-intensive businesses, like professional services and construction, held 23 days at the median, against 38 for capital-intensive ones. The Federal Reserve's Small Business Credit Survey keeps finding the same pressure points, too. The Atlanta Fed's summary of the 2025 survey for its region lists paying operating expenses and managing uneven cash flow among the most common financial challenges firms reported.

A reviewed close is strong insurance against that kind of unpleasant surprise.

What a controller adds

The forecast itself is usually built by whoever owns cash planning, often a fractional CFO. The controller's job is to make sure the starting point is right and the forecast gets better over time:

1. Close the month with every bank, card and merchant account reconciled, so starting cash is real.
2. Review receivables line by line and flag anything that's old, disputed or billed ahead of the work.
3. Make sure every bill received is recorded in payables, with its due date, and flag any disputed or lingering balances.
4. Record payroll taxes, benefit contributions and sales tax owed as liabilities, and include their payment dates in the forecast.
5. Track customer deposits and deferred revenue, and include the remaining costs of fulfilling those commitments in projected spending.
6. Compare last month's forecast to what actually happened, explain the big misses, and adjust the assumptions.

That last step is where forecasts get good. A forecast that's checked against actual results leads to learning how your customers pay and when your costs land, and becomes a tool you can rely on for hiring, spending and other important decisions.

What it looks like in practice

At EV Connect, one of our first priorities was setting up a 13-week cash forecast on a weekly cadence, during a stretch of fast growth that led to the company's acquisition by Schneider Electric in 2022. CEO Jordan Ramer described the situation plainly: "We had a spiky level of cash-flow activity," and "Being able to watch that was critical."

Three checks before you trust your forecast

Before you make a decision off your next cash forecast, ask three questions. Were all the bank and credit card accounts reconciled at the last month-end? Has someone reviewed receivables for anything that won't actually be collected on schedule? Are unpaid bills, customer deposits and payroll taxes all sitting on the balance sheet as liabilities? If any answer is "I'm not sure," the forecast is starting from an estimate, and we'd be glad to help you fix the starting point.

For more on what a monthly review catches beyond the bank feed, read Everything's Coded in the Bank Feed. Why Does Anyone Need to Review the Books?

This post is general information, not accounting, tax or financial advice. Talk to your advisors about your specific situation.