Payments on Account: Why Self-Employed Tradespeople Get Hit With a Bigger Tax Bill Than Expected

There is a specific moment that catches a lot of self-employed tradespeople.

You get through your first proper year on your own. You file the tax return. You expect a tax bill, because you are not daft.

Then the number appears and it looks wrong.

Not a bit wrong. Ridiculous wrong.

That is usually the moment you meet payments on account.

What are payments on account?

Payments on account are advance payments towards your next Self Assessment tax bill.

In plain English, HMRC looks at what you owed last year and assumes you may owe something similar this year. So instead of waiting until next January to collect all of it, they ask for money upfront in two instalments.

That is why your January bill can feel brutal.

You may be paying:

the balancing payment for last year
the first payment on account for the current year
then another payment on account in July

For new sole traders, it can feel like HMRC has doubled the bill overnight. It has not exactly doubled it, but it can feel that way if you have not planned for it.

A simple example

Say your Self Assessment tax and Class 4 National Insurance bill for the year is £4,000.

In January, you may need to pay that £4,000 as the balancing payment.

But HMRC may also ask for your first payment on account for the next year. That is usually half of last year’s bill.

So the January payment becomes:

£4,000 balancing payment
£2,000 first payment on account
Total due in January: £6,000

Then in July, the second payment on account is due:

£2,000

That is the bit that shocks people.

It is not a fine

Payments on account are not a punishment. They are not an extra tax. They are advance payments towards the next bill.

If your actual tax bill for the following year is lower, the difference can be adjusted. If your actual tax bill is higher, you may still owe more later.

But that does not make the cash flow problem any less real. A payment that is technically an advance still has to come out of your bank account.

Why tradespeople get caught out

Most employed people never see tax this way.

When you are on PAYE, tax comes off before the money hits your account. When you are self-employed, the full money lands in your bank. You pay materials. You pay fuel. You buy tools. You cover insurance. You pay yourself. Then months later HMRC wants its share.

The problem is that the tax money has often already been spent.

January is also a rough month for a lot of tradespeople. Weather slows jobs down. Customers are recovering from Christmas. New work can take a few weeks to get moving. Then HMRC lands on top.

That is why leaving tax planning until January is a terrible system.

How much should you set aside?

There is no perfect percentage because everyone’s numbers are different.

But the principle is simple. Every time you get paid, move tax money out of reach.

Not mentally. Actually move it.

Have a separate tax pot. Treat it like money that is not yours.

If you are under CIS, remember that deductions may already have been taken from your labour. That can reduce what you owe or even create a refund, but only if your records are right.

Do not guess. Track it.

What if this year is worse than last year?

This matters for tradespeople because income can jump around.

You might have one strong year followed by a slower year. You might lose a contractor. You might take time off. You might have a van disaster or a quiet winter.

If your income has dropped, your payments on account may be too high. You may be able to ask HMRC to reduce them, but do not do this casually. If you reduce them too far and still owe the tax, interest can become a problem.

This is one of those areas where a quick accountant conversation can save a lot of stress.

How Dayrates helps

Dayrates is built for tradespeople who do not want to run their business from memory.

Invoices, receipts, CIS records and accountant-ready paperwork all matter because tax planning depends on clean records.

If your records are a mess, payments on account feel like an ambush. If your records are up to date, you can see the hit coming.

That does not make tax fun. Nothing does. But it does make it manageable.

Final word

Payments on account are one of the least understood parts of going self-employed.

They are not a scam, and they are not a fine. But they are a serious cash flow problem if you do not plan for them.

Put tax money aside as you go. Keep your invoices and expenses organised. Track CIS properly. Know what January and July might look like before they arrive.

The worst time to learn about payments on account is when the bill is already due.