Here is the founder question: "We are launching a supplement subscription in eight weeks and everyone keeps asking for the 90 day forecast. I can build a revenue sheet, but I do not trust it. What should the first 90 days actually look like for a supplement subscription brand, and how much cash do we really need to hold to get through them?" Here is the direct answer: forecast four things on one page instead of one, a subscriber build, the cash that actually reaches your bank, the stock you have to commit to, and the cost base that runs without asking. In the illustrative example below, a brand adding 120, then 160, then 200 subscribers a month at £35, with a £30 cost to acquire each one, needs roughly £14,000 of accessible cash to get through day 90 while its monthly P&L loss narrows to about £1,100 in month three. The problem is often the order of events, and the order of events is forecastable.
We specialise in UK ecommerce brands generating £1m to £20m, and a common first quarter risk is that the P&L improves every month while the bank account gets worse. Founders forecast the profit and loss because it is the statement they understand. The bank statement is the one that decides whether month four happens.
Here's the Short Version
- Forecast four lines, not one: the subscriber build, cash collections, stock commitments and the cost base
- Cash is not revenue. If you are VAT registered, every £35 payment includes £5.83 of output VAT, and any amount received before you supply the box is deferred income
- Settlement lag on your own site is real but short: Shopify Payments settles United Kingdom charges in three business days, Stripe on a T+3 basis. Charged on Monday, spendable next week
- Your churn number is born at the first renewals. Until then, plan at 10% a month and stress at 15%
- Stock runs ahead of revenue. In the example, 829 boxes ship in the quarter from an order paid for before day one, and the next order is committed in month two
- Fund the stress case, not the base case. At a 30% worse acquisition cost the need goes from about £14,000 to about £18,000
- One page, checked every Monday, with the output VAT moved into a separate reserve the day it arrives
The Forecast Has Four Moving Parts
A weak 90 day forecast is a revenue forecast wearing a costume. Revenue is the easiest line to build and the least useful one to trust, because a subscription brand's first quarter is decided by timing, not totals. Four moving parts decide it: the subscriber build, meaning who pays this month; the collections, meaning when the money actually lands in the bank; the stock commitments, meaning what you must buy before the demand exists; and the cost base, meaning what leaves the account whether or not you sell anything. Build them in that order, on one page, and the question of how much cash you need becomes arithmetic instead of anxiety.
The Subscriber Build Comes First
Start with people paying, not pounds booked. The build is simple arithmetic: new subscribers each month, plus renewals, minus everyone who churns at their renewal. Then multiply by the price per box.
Illustrative example with synthetic numbers. The brand charges £35 a month and adds 120 subscribers in month one, 160 in month two and 200 in month three. Churn is 10% at each renewal, so each cohort recharges at 90% strength: the first cohort of 120 becomes 108, then 97, and the month two cohort of 160 recharges as 144 in month three.
| Month 1 | Month 2 | Month 3 | |
|---|---|---|---|
| New subscribers | 120 | 160 | 200 |
| Renewals at 90% | 0 | 108 | 241 |
| Subscribers charged | 120 | 268 | 441 |
| Cash collected | £4,200 | £9,380 | £15,435 |
Read the last row against the month before it. Nothing in month three is heroic, no viral moment, no launch spike, just compounding doing its work: 441 subscribers charged at £35 is a £15,435 monthly run rate by day 90, and £29,015 collected across the quarter. That compounding is why subscriptions are worth building. It is also why the cash plan is built around events, because every one of those payments arrives with strings attached.
Three notes on the build before you move on. First, 10% monthly churn is a planning assumption, not a law of nature: write it down, then add a stress line at 15%. Your real number arrives at the first renewal cycle, so treat the first three renewal dates as a fact finding mission rather than a scoreboard. The churn versus cash question has its own discipline, and we covered it in churn and cash flow for subscription brands. Second, if you bill on a 28 day cycle instead of calendar months, a subscriber who stays a year pays 13 times, not 12, which is a genuine gift to the model. Third, if you have not settled the price yet, start there: the margin maths behind a 28 day supplement box is its own exercise, and we walked through it in how to price a 28 day supplement subscription.
What Actually Reaches Your Bank
Charged is not collected, and collected is not spendable. On your own site the lag is short, but it is not zero. Shopify Payments settles United Kingdom charges in three business days, and Stripe settles standard UK card charges on a T+3 basis, then each pays out to your bank on your payout schedule, with a little more bank processing after that. Charged on a Monday, spendable the following week is a fair planning assumption. Reconciling payouts to your orders is a weekly job of its own, and we broke it down in how to reconcile Shopify payouts.
Then there is the line nobody forecasts: the renewals that fail. A declined card collects nothing. Whether the box ships and how retries work depends on your fulfilment and subscription settings. If your app is configured to retry failed payments, treat any recovered payments as upside rather than base case.
Now the two items that make your bank balance disagree with your P&L. The first is VAT. For VAT purposes, a supplement of the kind you are selling is standard rated: HMRC's food guidance treats dietary supplements of a kind not normally bought and eaten as food, including vitamin and mineral supplements of all kinds, as standard rated. If you are VAT registered, one sixth of every £35 you charge is output VAT. It is £5.83, the same amount as 20% of the £29.17 net price. It lands in your bank account with the payment, and it can look spendable for weeks. Your VAT payment is normally due one month and seven days after the accounting period ends, and the amount due may be lower after recoverable input VAT. The discipline that keeps subscription brands out of trouble is brutal and simple: the day a settlement lands, move a sixth of it into a separate reserve. Treat that reserve as unavailable working capital until you calculate the return, because the week it leaves will be the week your stock order also wants paying.
The second item is deferred income. If you charge before you supply the goods or services covered by the payment, the unearned amount is a contract liability, often called deferred income, not turnover. Your bank balance says you have the cash, while your accounts say you still owe the customer the supply, and both are correct. This is why a first quarter P&L can show a loss while the founder is certain the company is "actually profitable". The P&L is not being pessimistic. It is being honest about what has been earned.
Two more VAT notes. If your taxable turnover passes £90,000 in any rolling 12 months, or you expect it to pass £90,000 within the next 30 days, you must register. You may choose to register from launch too, and if you import stock that is often worth doing: to use postponed VAT accounting, your business must be registered for UK VAT, and you will need the relevant EORI number for your imports. And if you ever launch a multi month prepay plan, take advice first: taking payment early generally moves the VAT tax point to the day the money arrives, so a large prepay carries an early VAT bill. It is planable, but only if you plan it.
Stock Is a Commitment, Not a Variable
Subscription stock planning can look simpler than marketplace stock planning, and that can lull founders. In this illustrative model, demand is subscriber count times one box. Predictable is not the same as flexible. In the example, the quarter's shipping demand is 120 plus 268 plus 441, which is 829 boxes, and that stock had to be paid for before the first subscriber arrived. The first order was 1,000 boxes at £8 landed, so £8,000 left the business around launch, before a single renewal had been tested.
Then comes the trap that catches growing subscriptions: your stock commitments run a quarter ahead of the revenue they serve. In this illustrative plan, allow nine to thirteen weeks from deposit to sellable stock, and confirm the timeline with your supplier and freight forwarder. That lead time means the next order has to be committed while you are still learning your own churn rate, and its deposit lands inside the quarter you are forecasting. In the example, the next order of 1,800 boxes is committed in month two and its 30% deposit, £4,320, leaves in month three, while the first order is still selling through. That is not bad planning. That is what a growing subscription looks like from the inside, and the forecast exists to make it visible. We mapped the full order cycle timeline in the cash flow plan for a supplement brand buying stock from China.
The Cost Base That Runs Without Asking
Three cost lines complete the forecast, and these three are easy to underforecast when you are watching revenue. Advertising is the first: your planned new subscribers multiplied by your cost to acquire each one. In the example that is £14,400 across the quarter, and it is the single largest line in the whole plan, which is why the stress test below matters more than the base case. Acquisition costs are the number that moves. Second, the per box costs: fulfilment and postage around £3.50, and card fees around 85p on a £35 charge. Stripe's published UK rate for standard cards is 1.5% plus 20p, premium and international cards cost more, so model a blend rather than the best case. Third, the fixed base: tools, apps, the subscription software itself, insurance, compliance and admin, £2,500 a month in the example, none of which flexes down because a month was slow. Corporation tax arrives later: it is normally due nine months and one day after the end of your accounting period if taxable profits are up to £1.5 million, although associated companies can reduce that threshold. Founder pay belongs in the plan only when the numbers can genuinely afford it.
The First 90 Days in One Table
Here is the whole model assembled. Same illustrative numbers, figures rounded to the pound, VAT quarantined the day it arrives.
| Month 1 | Month 2 | Month 3 | |
|---|---|---|---|
| Cash collected from subscribers | £4,200 | £9,380 | £15,435 |
| Output VAT reserve, one sixth | (£700) | (£1,563) | (£2,573) |
| Ad spend | (£3,600) | (£4,800) | (£6,000) |
| Fulfilment and card fees | (£522) | (£1,166) | (£1,919) |
| Fixed costs | (£2,500) | (£2,500) | (£2,500) |
| Stock, first order and next deposit | (£8,000) | (£4,320) | |
| Month movement | (£11,122) | (£649) | (£1,877) |
| Funding needed by month end | (£11,122) | (£11,771) | (£13,648) |
The bottom row is the sentence you take to your bank or your investor: this plan needs about £14,000 of accessible cash, and on these month end figures the deepest point is the end of month three, not week one. Two things push it down even while revenue compounds: the gross output VAT reserve, about £4,836 across the quarter before any recoverable input VAT, and the next order's £4,320 deposit, leaving before its revenue exists. If that feels counterintuitive, good, it is supposed to. A subscription brand that grows on plan spends ahead of its own success, and the months after day 90 bring the VAT payment, the order balance and another ad month. That is exactly why your funding target is set by the stress case, not by this table.
Stress the Plan Before You Trust It
Three tests, run before you commit to anything:
- Acquisition costs up 30%. A cost of £39 per subscriber instead of £30 takes the funding need from about £14,000 to about £18,000. This is the stress that matters most, because ad costs are the least controllable line in the model and the easiest one to lose control of.
- Churn at 15% instead of 10%. Surprisingly calm in the first quarter, landing within about £700 of the base case, because churn needs time to compound. Do not take comfort from that. Run the same stress across twelve months and a 10% churn base keeps 28% of a cohort after a year, while a 15% base keeps 14%. The first quarter checks whether the machine starts. Churn decides how big the machine gets.
- One stock slip. Stress a four week delay on the next order. If your stock cover runs out, model the lost sign-ups, renewal handling, refunds and paused ads, so you know the cost of being late. Then order with buffer, because the delay you model is rarely the delay you get.
Then set your funding target at the stress number, not the base case. If the stress number is unfundable right now, grow slower. A smaller plan that survives beats a bigger plan that dies in week ten. This is the place subscription founders get hurt by optimism, not by competition.
What to Check Every Single Week
One page is only worth building if it gets read. Five minutes every Monday, five numbers: subscribers added against plan; renewals against your churn assumption; blended acquisition cost; the cash balance against plan, with the VAT pot counted separately; and stock cover in weeks against your supplier lead time. Two or more red for two consecutive weeks means something pauses, normally ad spend, until the plan catches up. It is the same discipline we use with hypergrowth brands: forecast weekly, review weekly, and never let the plan go stale. We wrote the wider version of that routine in cash flow forecasting for hypergrowth brands.
FAQ
What should a supplement subscription forecast show month by month?
Four lines: the subscriber build of new, renewals and churn; the cash that reaches your bank after settlement timing and the VAT you set aside; the stock commitments including the next order's deposit; and the cost base of ads, per box costs and fixed overheads. One page, updated weekly, with a base case and a stressed case side by side.
How long does subscription money take to reach the bank?
On your own site, plan on about a week. Shopify Payments settles United Kingdom charges in three business days, Stripe settles standard UK card charges on a T+3 basis, and each then pays out on your schedule with bank processing after that. Failed renewals collect nothing, so treat any recovered failed payments as upside rather than base case.
How much cash does a supplement subscription brand need for its first 90 days?
Enough to survive the stressed version of your own plan. In the illustrative example that is about £14,000 in the base case and about £18,000 if acquisition costs come in 30% worse, with a gross output VAT reserve of about £4,836 held separately from spendable cash. If you cannot fund the stress case, scale the plan down until you can.
The Bottom Line
A supplement subscription is one of the best business models in ecommerce and one of the worst first quarters, for the same reason: the money you collect serves the month you are in, while the commitments you make serve the quarter you are not. So forecast the order of events rather than the size of the dream. Build four lines on one page, quarantine the VAT from day one, commit stock a quarter ahead with your eyes open, and fund the stress case instead of the pretty one. Do that, and the compounding takes care of the rest.
If you would rather have your 90 day model built, stressed and ready for your bank, that is our daily work. We are specialist social commerce accountants for UK ecommerce brands generating £1m to £20m, and forecasting and cash flow planning is one of our core services. Book a call and bring your subscriber numbers, and we will build the first version with you.