Congratulations, and check your cash before you celebrate too hard, because growth consumes cash before it produces any. A big new client means weeks or months of spending on delivery, staff, materials, your time, before their first payment lands. Businesses have been sunk by the best sale they ever made, and the difference between a windfall and a crisis is usually preparation, not luck.
How much cash do I need for a big new client?
The formula is simple: monthly delivery cost × months until you're paid = cash you need to float.
Say the new client is worth $15,000 a month, and you invoice at each month's end with 30-day terms. You'll spend money delivering their work for roughly 60 days before the first dollar arrives. (That 60-day figure depends on your billing terms and how fast they actually pay, so treat it as an example, not a fixed rule.) If delivering their month costs you $9,000 in labor and materials, you're floating around $18,000 of your own cash before payment one. That $18,000 is money you spend before you're paid. The bigger the client, the bigger the hole you dig before the payoff starts.
The three checks before you fully commit
Cash. Can your account absorb the gap? Run the math above for your actual terms and costs, subtract it from your typical monthly low point, and see if you stay comfortably positive through the ramp-up months. If not, the fixes are negotiable before you start and awkward after: a deposit or upfront retainer, milestone billing instead of monthly, or shorter payment terms. Asking a new client for a deposit is normal and professional. Asking them to pay early because you're squeezed in month two is not, and it puts the relationship under strain before it's begun.
Capacity. Who actually does this work? If the answer is "me, in the hours I currently don't have," the client will be served by a tired version of you and your existing clients will feel the difference. If the answer involves hiring, layer in the hiring math too, because now you're carrying the new payroll and the payment gap at the same time.
Concentration. What share of your revenue will this client be? Past roughly a quarter to a third of your total, you haven't just gained a client, you've gained a dependency, and their future decisions become your business's weather. That's not a reason to say no. It's a reason to keep selling as if you hadn't landed them. If one client is over 25% of your revenue, make new sales your top weekly priority until it's back under 25%.
The reframe worth keeping
Growth is not a prize you collect, it's a load you carry, and the carrying costs arrive before the rewards do. Owners who understand that don't grow slower. They grow with their eyes open, funding the gap on purpose instead of discovering it in their bank balance.