MTD Threshold Watcher — Side-Hustle Income Forecaster

Making Tax Digital for Income Tax is being phased in by income level — £50,000 from April 2026, £30,000 from April 2027, £20,000 from April 2028 — and most people don't realise they've crossed a threshold until it's too late to prepare. This watcher fixes that: type your gross income for each month as it finishes, and it projects your whole-year total and tells you, in plain English, exactly which MTD wave you're on track for.

The workbook includes:

• A monthly income log with a single seasonality dial that only adjusts months you haven't entered yet
• A projected annual income figure and an MTD verdict
• A threshold gauge showing headroom to each of the three lines and whether you're over or under
• Awareness strips for the £1,000 trading allowance and the £90,000 VAT registration threshold
• A 'How MTD Works' tab explaining the scheme, including the point people usually miss — the thresholds work on gross income, not profit

Every formula is checked with 96 automated tests, including a refund-heavy negative month, a £0 month, and every threshold tested exactly on the line and a penny either side. 96 of 96 checks pass, shown on the QA & Version tab.

This is a planning and awareness tool, not tax advice — it estimates when MTD will apply so you can prepare; it doesn't file anything or connect to HMRC.