Cash-flow forecasting: a 13-week direct forecast, scenarios and placing VAT and tax prepayments correctly
Build a rolling 13-week direct cash-flow forecast on a weekly grid, place VAT and tax prepayments in the right week, run a downside scenario and read the minimum cash point.
What you will learn
- Why a direct, weekly forecast catches problems that a monthly profit plan misses.
- How to build the 13-week grid: opening cash, receipts, disbursements, closing cash.
- In which week German VAT, income or corporation tax and trade tax prepayments fall due (as of 2026).
- How to run a downside scenario and define a minimum cash buffer.
Explanation
The course "Business Foundations" showed that a profitable business can run out of cash. The tool that prevents this is the 13-week cash-flow forecast: a table with one column per week for the next quarter, built with the direct method, meaning you list actual expected payments in and out rather than adjusting profit. Thirteen weeks shows the next VAT and tax dates and stays concrete. It is rolling: each week you drop the finished week, add a new week 13 and compare the last forecast with actuals.
The grid has four blocks. Opening cash (bank balances plus cash, minus any overdraft drawn). Receipts: customer payments by expected week, taken from open invoices and their payment terms plus a realistic estimate for new sales; other inflows such as a loan payout. Disbursements: payroll including social security contributions (due the third-to-last bank working day of the month), rent, suppliers, loan instalments, leasing, insurance, and the tax lines below. Closing cash = opening + receipts − disbursements, which becomes next week's opening.
Taxes are where most beginners go wrong, because they are large, irregular and have fixed dates. For Germany, as of 2026 and subject to change:
- Umsatzsteuer (VAT): the Voranmeldung and payment are due on the 10th of the month after the period. The period is monthly if last year's VAT payable exceeded €9,000, quarterly between €2,000 and €9,000, and only an annual return below €2,000. A Dauerfristverlängerung shifts the deadline by one month; monthly filers then pay a Sondervorauszahlung of one eleventh of last year's prepayments by 10 February, credited back in December. The amount you pay is output VAT on sales minus input VAT on purchases, so it is roughly 19 percent of your value added for the period.
- Einkommensteuer or Körperschaftsteuer prepayments: 10 March, 10 June, 10 September, 10 December.
- Gewerbesteuer prepayments: 15 February, 15 May, 15 August, 15 November.
Enter each of these in its due week; never spread them evenly. VAT collected from customers is not your money: many owners keep it in a separate account from the day it arrives.
A scenario changes assumptions, not arithmetic. The standard downside is "receipts 20 percent lower and one week later, costs unchanged". The minimum cash point is the lowest closing balance in the 13 weeks; compare it with your minimum buffer, a floor you define in advance (for example one month of fixed costs). If the downside breaks the floor, you act now: chase receivables, delay a purchase, draw the overdraft or arrange a loan while you still can.
Worked example
Hypothetical example: a small agency, opening cash €10,000, quarterly VAT filer, weeks 1 to 6 of the forecast shown (weeks 7 to 13 continue the same way). Week 2 contains the 10th of the month, so the VAT payment of €6,200 falls there; week 4 is month end with payroll €11,000; week 6 contains 10 June with an income-tax prepayment of €4,500. Rent €2,500 is paid in weeks 1 and 5; suppliers €3,000 every week. Bank fees and interest are ignored.
| Week | Receipts € | Disbursements € | Net € | Closing cash € |
|---|---|---|---|---|
| 1 | 9,000 | 5,500 | +3,500 | 13,500 |
| 2 (VAT) | 6,000 | 9,200 | −3,200 | 10,300 |
| 3 | 14,000 | 3,000 | +11,000 | 21,300 |
| 4 (payroll) | 7,000 | 14,000 | −7,000 | 14,300 |
| 5 | 5,000 | 5,500 | −500 | 13,800 |
| 6 (tax) | 12,000 | 7,500 | +4,500 | 18,300 |
Base case: minimum cash €10,300 in week 2. Total receipts €53,000, disbursements €44,700.
Downside (receipts × 0.8, same timing): week 1 closing €11,700; week 2 €7,300; week 3 €15,500; week 4 €7,100; week 5 €5,600; week 6 €7,700. Minimum cash €5,600 in week 5. If the agency's floor is €8,000 (already thin against monthly fixed costs), the downside breaks it in weeks 2, 4, 5 and 6. The owner should secure an overdraft line or bring forward collections before week 2, not after.
Common mistake
Practice activity
On paper: a trader's net sales in April are €30,000 (19 percent VAT on top) and VAT-bearing purchases are €12,000 net. The business is a monthly VAT filer with a Dauerfristverlängerung. Calculate the VAT payment and name the week-of-month in which it leaves the account. Then state the closing cash if the account holds €9,000 just before the payment and nothing else moves.
Show solution
Output VAT: €30,000 × 0.19 = €5,700. Input VAT: €12,000 × 0.19 = €2,280. Payment: €5,700 − €2,280 = €3,420.
Without extension the April return is due 10 May; with Dauerfristverlängerung it is due 10 June, so the payment sits in the week containing 10 June (the same week as the income-tax prepayment, which is why June and December are often tight).
Closing cash: €9,000 − €3,420 = €5,580.
Limitations: ignores the Sondervorauszahlung, non-deductible input VAT, the three-day grace period for bank transfers and any corrections from the annual return.
Key takeaways
- Forecast actual payments by week; roll the table forward every week and compare with actuals.
- Place VAT (10th, or one month later with extension), income or corporation tax (10 March/June/September/December) and trade tax (15 February/May/August/November) in their exact weeks.
- Define a cash floor in advance and test it against a downside of 20 percent lower, one week later receipts.
- Arrange financing when the forecast shows a gap, not when the account is empty.
Next step
The biggest lever in most forecasts is how fast customers pay and how much cash sits in stock; lesson 9 measures this with the cash conversion cycle.
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