What will be in the bank over the next 13 weeks?

The most uncomfortable question in a management meeting is usually "Can we cover salaries and check payments on the 15th?" The answer is often given by looking at the bank balance and adding a bit of gut feeling. Yet your ERP already knows the receivables coming due, the checks to be paid and the pending orders for the weeks ahead. In this article we explain the steps to build a weekly cash flow forecast from ERP data, where each item comes from and how to keep the forecast realistic.

Why weekly and not monthly?

A monthly cash plan works for budgeting, but it hides squeezes. Cash can look positive for the month as a whole while there is a serious gap in the second week: if large check payments cluster mid-month and collections cluster at month end, the monthly table will not show it.

The common practice is a 13-week rolling forecast: roughly one quarter. Each week, the past week drops off the table and a new week is added. That way the near term is clear, and you also have a rough picture of the next quarter.

The skeleton of the forecast

A weekly cash forecast rests on a simple equation:

Closing cash = opening cash + forecast inflows − forecast outflows

The difficulty is not in the equation but in estimating inflows and outflows realistically. The ERP holds a large share of these items already:

Estimating inflows realistically

The most common mistake is assuming customer receivables will be collected on the due date. In reality, every customer has their own payment habits. By looking at historical data, you can answer "how many days after the due date does this customer pay, on average?" for each customer or customer group, and add that shift to the forecast.

With example figures: if a receivable of TRY 500,000 is due on March 10 and the customer has paid an average of 12 days late in the past, the forecast should place it in the week of March 22. This small correction alone noticeably improves the forecast's accuracy. A receivables aging report is a good starting point for seeing which customers are late and by how much.

Capturing outflows completely

The outflow side is usually more predictable, but forgotten items throw the forecast off. Rent, insurance premiums, annual license renewals, advance tax payments and capital expenditures may not be tied to an invoice in the ERP. List them once as a "recurring payments calendar" and add them to the forecast.

Thinking in scenarios

A single forecast figure shows the most likely outcome, but management decisions are often made based on what happens in a bad case. That is why it helps to add two simple scenarios to the table. In the cautious scenario, shift collections from your few largest customers by two weeks and halve the sales expected from open orders. In the expected scenario, use historical payment habits as they are. The gap between the lowest cash points of the two scenarios gives you a concrete sense of how much buffer cash or available credit line you need. That buffer lets you talk to the bank ahead of time and on better terms, not at the last minute.

Testing the forecast: comparing with actuals

A forecast only improves when you look back and check it. At the end of each week, fill in this table:

• Forecast inflow versus actual inflow, and the difference
• Forecast outflow versus actual outflow, and the difference
• The reason for the difference (late-paying customer, unexpected expense, early payment)

After a few weeks you will see which items deviate systematically and can adjust your assumptions accordingly.

Weekly cash forecast checklist

• Does the opening balance cover all bank accounts and petty cash?
• Are customer receivables placed by payment habit rather than due date?
• Are due dates of checks in the portfolio and risky drawers flagged?
• Are salaries, social security, taxes and loan installments on the calendar?
• Have recurring payments with no invoice in the ERP been added to the list?
• Has the worst case (your three largest customers pay two weeks late) been calculated?
• Is the forecast compared with actuals every week?

How we do it at Globya

For companies using the common ERP and finance platforms on the market, led by Netsis and Logo, the ERP systems widely used in Türkiye, READERP comes with ready-made Cash and Receivables views; it connects to the ERP read-only, never writes a single row and is installed the same day. You can ask questions such as "How much in checks comes due over the next four weeks?" in plain Turkish. For needs specific to your company, such as a 13-week forecast table, we prepare custom financial reports; this work falls under our ERP and reporting service. If you are curious about the structural cause of cash squeezes, our article on the cash conversion cycle is a good next read.

Frequently asked questions