SA303

The SA303 form is a document that you can fill in and send to HMRC if you’re self-employed and want to reduce your Payment on Account. You can also use the online Self Assessment service if you don’t want to deal with printing and sending it by post.

How does Payment on Account work?

HMRC expects anyone earning more than 20% of their income outside of employment to pay tax using Payment on Account.

On your first Self Assessment tax return, you’ll have to pay the entire bill, of course. You’ll also have to pay an extra amount. HMRC calculates half of your last tax bill and add it on as an advance payment for this year’s tax bill. Why? Because you can never be too sure who’s planning on paying last year’s tax bill and not this year’s…

If you owe £5,000 in tax, you’ll have to pay an extra £2,500 on top of this to cover part of your next tax bill.

You’ll pay your tax bill and the advance payment before the 31st of January. The next half is due before the 31st of July. If you’re newly self-employed, you may be shocked to find you could end up paying a tax bill up to 50% higher. But fret not, if your next tax bill turns out to be less, your Payment on Account will be adjusted by HMRC to accommodate for the previous overpayment. On the other hand, if you earn more than expected, then you’ll have to pay more tax. This is called a balancing payment.