Tax Reserve Calculator

A tax bill you set nothing aside for is the surprise that hurts most. This calculator works out how much to hold back each month, so the money is already waiting when the bill lands. From your monthly sales and expenses it estimates an amount to reserve for VAT, income or corporation tax and National Insurance or PRSI.

What It Does

The Tax Reserve Calculator covers United Kingdom, Ireland and Other. The country you pick sets the currency (pound, euro or dollar) and the default tax rates for where you trade.

You choose from three business types:

• Self-Employed and Sole Trader reserve for Income Tax plus National Insurance (PRSI in Ireland).
• Limited Company reserves for Corporation Tax, and no National Insurance.

From your monthly sales and expenses it shows a Monthly Tax Reserve, an Annual Tax Reserve, a breakdown by tax type, and your net profit after income or corporation tax and National Insurance. The VAT figure applies the VAT rate to your monthly profit as a planning estimate, so check the exact amount against your VAT return when it is due.

Nothing here is tax advice or a compliance guarantee. It is a planning estimate to help you set money aside, and your accountant still owns the return. The Tax Reserve Calculator is on the Plus plan.

The Short Version

1. Pick your Country and Business Type.
2. Enter your Monthly Sales and Monthly Expenses.
3. Check the default tax rates, or switch on Use Custom Tax Rates.
4. Click Calculate Tax Reserve and read your monthly reserve.

The rest of this guide walks through each step.

Enter Your Business Details

Start with your Country. It sets the currency and the default tax rates for your region.

Then choose your Business Type. It decides which taxes apply: a limited company reserves for Corporation Tax, while Self-Employed and Sole Trader reserve for Income Tax and National Insurance.

Now enter your Monthly Sales and your Monthly Expenses. These are monthly figures, not annual, and both are needed before the tool can work out your reserve.

Check Or Override The Tax Rates

While Use Custom Tax Rates is off, the tool shows the default rates it will apply as small chips: your VAT rate, your income or corporation tax rate, and your National Insurance or PRSI rate for the country and business type you picked.

Turn Use Custom Tax Rates on to enter your own VAT, tax and National Insurance rate, each from 0 to 100%. Use it for flat-rate VAT, a reduced rate, or any situation where the defaults do not match yours.

One thing to know: changing your Country, your Business Type or the Use Custom Tax Rates switch clears the last result. Click Calculate Tax Reserve again after any of these to refresh the figures.

Read Your Reserve

Click Calculate Tax Reserve. The results appear in the panel on the right, or below your inputs on a phone. Nothing shows until you click it.

The headline is your Monthly Tax Reserve: the amount to move into a separate tax pot each month. The Annual Tax Reserve sits below it.

The Monthly Breakdown splits the reserve into VAT, Income Tax or Corp. Tax, and National Insurance or PRSI. Net Monthly Profit and Net Annual Profit show what is left after income or corporation tax and National Insurance.

If you run a UK limited company, a note reminds you that employer's National Insurance and other payroll tax are not included. Hand those, and the final return, to your accountant.

After a result, the same button reads Recalculate. Change a figure and click it again to update.

See The Full Breakdown

Open Calculation Breakdown for a line-by-line table: your sales and expenses, monthly and annual profit, each rate applied, each tax amount, and the monthly and annual reserve totals.

It is the working behind the reserve, so you can see exactly how each figure was reached. Treat it as a planning estimate, not a guaranteed bill.

Save, Share Or Download

You can also tap Print/Save Report in the header for a printable PDF to file with your accounts.

Tips And Best Practices

• Open a separate savings account. Move your monthly reserve across on the same day each month. When the tax bill arrives, the money is already there.
• Treat the VAT figure as a planning estimate. It applies the VAT rate to your profit, so check it against your actual VAT return before you rely on it.
• Review each quarter. When your sales rise or fall, update the monthly figures and recalculate, so the reserve stays close to reality.
• Use Custom Tax Rates for anything non-standard. Flat-rate VAT, reduced rates or a different threshold all go in by hand.
• Price from your own overheads if your net profit looks thin. Not the shop down the road. Work out your real cost base with the Operating Cost Calculator, then set your markup with the Business Markup Calculator.

Common Questions

Is this tax advice? No. It is a planning estimate to help you set money aside. Your accountant owns your return and any advice specific to your business.

Does it cover limited companies? Yes. Choose Limited Company and it reserves for Corporation Tax instead of Income Tax, with no National Insurance row. In the UK it also uses marginal relief between the small-profits and main rates. Employer's National Insurance is not included.

What is the difference between NI and PRSI? National Insurance is the UK term and PRSI is the Irish equivalent. The tool picks the right label automatically from the country you choose.

Why is the VAT based on my profit? It is a planning estimate to sit alongside your tax reserve, not your exact output-minus-input VAT. Confirm the real figure against your VAT return when it is due.

What if my income varies month to month? Use an average of your monthly sales and expenses, then update it each quarter so the reserve keeps pace with your trade.

I do not charge VAT, or my rate is different. How do I set that? Turn on Use Custom Tax Rates and set your own VAT rate. Enter 0% if you are not registered, then click Calculate Tax Reserve again.