Tool Guide

The VAT Cash Flow Planner
guide for UK SME owners

VAT is the most predictable large outflow in any VAT-registered business — yet it still catches SME owners out every quarter. This tool calculates your exact quarterly liability, how much to set aside monthly, and whether your current cash buffer is adequate.

Watch how it works

Real inputs. Real outputs. See exactly what you get before you commit to anything.

lumixai.co.uk/vat-cash-flow-planner

This is a live preview of the VAT Cash Flow Planner — the same tool available to all subscribers.

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What the PDF report looks like

Every tool generates a downloadable PDF report — structured like a professional consultant's analysis, built from your actual data. Below is an example using dummy data.

LumixAI — VAT Cash Flow Planner Report — Example Data Example only
EXAMPLE
£28,800
Quarterly VAT liability
£9,600
Monthly set-aside
17.2%
As % of net revenue
Q2 2026
Next payment due
Adequate
Cash reserve status
Free
No sign-up needed
Quarterly VAT liability of £28,800 requires £9,600 set aside monthly. Current cash balance of £38,000 covers 1.3 quarters — above the minimum recommended 1.25 quarters. Recommend a dedicated VAT reserve account to prevent working capital confusion.

Why VAT still catches SME owners out — and how to prevent it

VAT is the most predictable large financial event in any VAT-registered business. The liability date is known in advance. The approximate amount can be calculated from revenue. The payment date is fixed. Yet VAT bills still cause cashflow crises for SME owners every quarter — not because the bill is a surprise, but because the cash to pay it was spent on other things in the intervening weeks.

The core problem

When a VAT-registered business collects payment from a customer, the full amount — including VAT — arrives in the bank account. The VAT component is not the business's money. It belongs to HMRC and is due at the end of the VAT quarter. But because it sits in the same account as genuine working capital, it is easy to treat it as available cash — and some of it gets spent.

The result is that at quarter end, the business needs to pay a VAT bill that is partly or fully composed of money that has already been spent. If the shortfall is significant, the business either needs to find the cash elsewhere or request a time-to-pay arrangement with HMRC — both of which consume time, create stress, and may carry interest or penalties.

The solution: a dedicated VAT reserve account

The simplest and most effective solution is a dedicated savings account used only for VAT. At the point of each customer payment, transfer 16-17% of the net amount received into the VAT account. By the time the VAT quarter ends, the money is already there — ringfenced and unavailable for other purposes. The main current account never shows a balance that includes VAT, so the temptation to treat it as working capital does not exist.

What the VAT Planner calculates

The tool takes your annual turnover and VAT scheme, calculates your quarterly liability, determines the monthly set-aside amount required, and assesses whether your current cash balance provides adequate cover. It also generates a payment schedule showing the next four quarterly payment dates so you can plan cashflow around them.

Who it is for

Any VAT-registered SME owner who has ever been stressed about a VAT payment, found themselves short at quarter end, or simply wants to confirm that their current cash management approach provides adequate VAT coverage.

Stop being surprised by your VAT bill.

The VAT Cash Flow Planner is free to use. No sign-up. No payment. Instant result.