How to see a cash crunch coming: a simple weekly cash flow check

Last updated November 2, 2026. All guides

Lay out the next four or five weeks from today’s balance. Set aside bills that come at a fixed time, such as rent and payroll, estimate everything else from the same dates in past months, and work out what’s left at the end of each week. Then check inside each week: if a big payment usually goes out before that week’s money comes in, your account can dip below zero even when the week ends fine.

What you need

• Your bank transactions for the last 90 days, with dates. Remove names and account numbers before you paste them anywhere, including an AI tool.
• Today’s balance and its date.
• Any big payment you know is coming in or going out.

Six steps

1. Set the weeks. Week 1 starts the day after your balance date. Lay out four weeks. If a fixed bill falls just after week 4, such as rent on the 1st, add a fifth week so you see it.
2. Set aside fixed bills. Rent, payroll and anything else that’s the same amount on the same day, or the same number of days apart, every time. Put each one in the week it falls.
3. Estimate everything else from the same dates. For a coming week of the 8th to the 14th, average what came in on the 8th to the 14th of each past month. Do the same for money going out, leaving out the bills you set aside. This keeps real patterns, such as customers who pay at the start of the month.
4. Round each week to the nearest $100. These are estimates.
5. Work out what’s left. The previous week’s Left, plus money in, minus money out. The week with the lowest Left is your tight week.
6. Check inside each week. Start from what the week begins with, and walk through the same dates last month day by day, with your fixed bills on their own dates. If the balance goes below zero, note when, by how much and which payment causes it.

Example: five weeks from $2,800

Week	In	Out	Left
1 (Nov 1–7)	$6,200	$5,100	$3,900
2 (Nov 8–14)	$4,100	$6,900	$1,100
3, tight (Nov 15–21)	$3,800	$4,600	$300
4 (Nov 22–28)	$5,600	$3,900	$2,000
5 (Nov 29–Dec 5)	$5,300	$4,400	$2,900

Week 3 is the tight week, but it ends with $300, so it looks fine. The check inside the week says otherwise. A supplier payment of about $3,500 usually goes out on the 15th, a day before customer money arrives. Starting the week at $1,100, the account could be up to about $2,400 short until card deposits come in around the 20th.

Week 5 is there because rent is due on December 1, three days after week 4 ends. Rent on November 1 is a smaller version of the same problem: it’s $3,200, and the balance is $2,800.

What these numbers leave out

• Bills that come less often than your history shows, such as quarterly taxes or annual insurance. Add them by hand.
• One-time payments. Decide whether each one belongs.
• Transfers between your own accounts, which aren’t money in or out.

What to do about a tight week

This check shows when money gets short, not what to do about it. Talk to your accountant about financing or which bills can move, and don’t plan to delay payroll or payroll taxes. Sometimes a customer will agree to pay a little earlier, or a supplier will agree to a later date, if you ask before the week arrives.

Questions

How far ahead should I look?

Four or five weeks is enough to act on, and estimates from past months get less reliable the further out you go. Run it again each week with a fresh balance.

Why not just use monthly totals?

A month can end fine and still have a week, or a day, where the money runs out. Weekly totals, plus the check inside each week, show when.