Your tax position, tracked, not re-typed.
The free calculator answers “what do I owe right now?” A subscription answers the harder question: “how is my position changing, and what's coming?” — which is where the real value is for anyone whose income isn't flat year to year.
Save every scenario
Stop re-entering the same numbers. Save a scenario once — “if I take this dividend,” “if I go self-employed” — and come back to it anytime.
Compare side by side
See exactly how two scenarios differ — this year vs. last year, or two ways of paying yourself — in one table instead of doing the subtraction in your head.
Deadline reminders
A nudge before each payment-on-account date, based on your actual saved figures — not a generic calendar reminder that doesn't know your numbers.
Why this isn't a “subscribe for a month, cancel” tool
We know the honest failure mode for a tool like this: someone subscribes, checks their numbers once, and cancels a month later having gotten everything they needed in one sitting. We'd rather design against that than pretend it won't happen.
The value here compounds, it doesn't front-load. Payments on account are inherently a multi-year chain — what you pay this January depends on last year's actual liability, and what you'll pay next January depends on this year's. A single visit only ever gives you one link in that chain. Staying subscribed through a full tax year is what actually lets Serenity Tax show you the whole timeline instead of a guess, and each year you stay, the year-over-year comparison gets more useful, not less — it's the opposite of a tool that's “done” after one use.
The reminders are the other half of it. A saved scenario isn't just a record, it's the thing a deadline reminder is calculated against. Cancel, and the next reminder doesn't go out — which is a real, felt loss the next time a payment date sneaks up on you, not an abstract “you're missing out” pitch.
In short: the free calculator is genuinely free and genuinely complete for a one-off “what do I owe” question. Subscribing is for the ongoing question — and we'd rather you subscribe for that reason than any other.