13-Week Cash Flow Tracker

Profit tells you whether the work was worth doing. It says nothing about whether the money is in the account on the Friday payroll runs. Plenty of profitable shops miss a supplier payment in week seven, for the dullest possible reason: the money went out before it came in.

Why thirteen weeks

Thirteen weeks is one quarter. It is the shortest window that holds a full cycle: jobs sold, built, invoiced, collected. Shorter and you only see the crunch once you are standing in it. Go longer and it stops being a forecast. You do not know which jobs land in week 34, and pretending you do fills the sheet with invented numbers. Six weeks of warning is enough to chase a slow payer or ask a supplier for net 45.

Build it weekly. A month that nets positive can still contain a Tuesday where the balance goes below zero.

Step 1: Invoice the day the work is finished

Raise the invoice the day the job is signed off, using the Free Invoice Generator. On net-30 terms, an invoice sent four days late costs you those four days plus the wait for the customer's next weekly accounts-payable run. Another seven. Do the invoicing on Sundays and you shift a quarter's collections two weeks right without one customer paying late.

Write the due date as a date. "Net 30" is arithmetic the reader has to do; "Payment due Monday, September 8, 2026" is a deadline. Include the invoice number, job address and the customer's PO reference. A missing PO is the most common reason an invoice sits unactioned while both sides assume it is in progress.

Under a few hundred dollars, skip terms altogether. A payment QR on the invoice (Venmo / CashApp QR Code Generator) turns a 30-day receivable into a same-day one. In the example, jobs complete at the end of weeks 2, 3, 5, 6, 8, 9, 11, 12 and 13.

Step 2: Forecast collection dates, not invoice dates

Put $14,600 in the week you invoiced and what you have written is a sales report with a date on it. Money belongs in the week you expect it to clear. That means a view of each customer built from your own history rather than the terms you printed on the paper: pull their last ten invoices, count the days from invoice to cleared funds, take the median.

Homeowners paying by card land in days. Commercial accounts land on or just after term. A general contractor working pay-when-paid lands when their client pays, so forecast that one pessimistically. The example uses six weeks from completion to cleared funds, which puts the job finishing in week 2 into cash in week 8. Five of the nine finish too late to collect inside the quarter.

Step 3: Give the terms teeth

Nobody is saved by a late fee. At 1.5% a month on $14,600 it works out to about $219 a month, roughly $7.20 a day. What it buys you is a place further up someone else's pay run and a defensible reason to chase. Model the mechanics in the Late Fee Calculator for Rent: grace period, flat versus percentage, and how the charge ages.

A grace period (five days is common) absorbs processing lag, so the fee only fires on real lateness. It must sit in the signed contract and be repeated on the invoice. One that first appears in an angry email is a term you invented afterwards. It also has to be within what your jurisdiction allows, which varies by state and is usually tighter for consumer contracts.

An unenforceable fee is worse than no fee at all. Back down once and you have taught that customer your terms are decorative. Worse, a disputed fee gives a slow payer grounds to hold the entire invoice while it is "resolved". You chased $219 and delayed $14,600.

Step 4: Set the floor the forecast must clear

Fixed costs do not wait for collections. Run the Break-Even Point Calculator with the job as the unit: $12,000 fixed, $14,600 price, $9,650 direct cost, $3,000 target monthly profit. Billing hours instead? The Service Business Break-Even Calculator takes an hour as the unit.

Contribution is $14,600 − $9,650 = $4,950 per job. Break-even is $12,000 ÷ $4,950 = 2.42 jobs a month. Clearing $3,000 of profit on top of that needs 3.03. So: three a month, nine in the quarter.

Write that $2,770 into all thirteen weeks before you enter anything else. It is due whether or not anyone paid you.

Step 5: Find the jobs that are profitable but cash-negative

Price the job in the Job Costing Calculator: $4,800 materials, 96 labor hours at $38, $1,200 subcontractor, 18% overhead, 22% target margin. Direct cost $9,648, loaded cost $11,385, price $14,596, rounded to the $14,600 used above. Take the hours off real time cards rather than memory. The Time Card Calculator counts breaks and overtime, and understating hours here understates every step below it.

Now read the same job as timing. Materials are bought in week one. Wages go out as the work happens, the subcontractor invoices at finish, and the customer pays six weeks after completion.

Every job here is profitable. Every job is also a seven-week loan to the customer. Book more of them and the hole gets deeper faster: growth consumes cash before it produces any.

Step 6: Build the grid and read the trough

Thirteen rows, opening balance $8,000. Cash in from Step 2's collection dates; cash out is Step 4's $2,770 floor plus Step 5's job outflows, with jobs starting in weeks 1, 2, 4, 5, 7, 8, 10, 11 and 12.

Nine jobs at $4,950 contribution is $44,550, less $36,010 of fixed cost. So the quarter earns roughly $8,540 of profit and ends $12,642 overdrawn. Both numbers are right. The difference is receivables: you started the quarter owed $43,800 and finished owed $73,000, five jobs uncollected, and that $29,200 of growth is the cash you cannot find.

Read the grid for two dates. The trough (week 7, −$12,806) sizes the facility you need. The first breach (week 6) is the deadline, and no monthly report would have put it in front of you that early.

Step 7: Fix it with timing, not margin

Take a 30% deposit on signing. That is $4,380 a job, received the week the job starts and deducted from the final invoice. Margin does not move, and no customer pays a cent more than before. Rerun the grid: week 7 becomes +$9,094, the quarter never goes negative at all, and week 13 closes at +$9,258. A $21,900 swing, purely from moving money earlier.

Progress billing does the same job on longer work. Bill at rough-in and again at materials delivery, and one seven-week loan turns into two short ones. Where a trough is unavoidable, price the bridge early: put $15,000 over 12 months into the Loan EMI Calculator and weigh the monthly cost against the $4,950 an extra job contributes. Arrange it in week 1, while the numbers still look good.

Then update the grid the same morning every week. Roll the window forward a row and replace the forecast numbers with what actually cleared. The customer who runs two weeks behind forecast every time becomes obvious inside a month of doing that, and by then you have the invoice number and the date to quote at them.