For many Self Assessment taxpayers, the biggest tax bill of the year arrives months after the income was actually earned.

That could change from April 2029.

HMRC has been consulting on proposals to make Income Tax Self Assessment (ITSA) payments more timely. The main confirmed change is that taxpayers who have both Self Assessment income and sufficient PAYE income will start paying more of their Self Assessment tax during the tax year through PAYE.

HMRC is also exploring whether other Self Assessment taxpayers should make payments more frequently throughout the year.

It is important to note that some of these proposals are still being considered, so the final rules may change.

How does Self Assessment payment work currently?

Under the current system, Self Assessment taxpayers generally pay the tax and Class 4 National Insurance due for a tax year by 31 January following the end of that tax year.

For example, tax and Class 4 National Insurance for the 2025/26 tax year will generally need to be paid by 31 January 2027.

Some taxpayers also have to make Payments on Account towards the following year’s tax bill.

Payments on Account normally apply where the previous year’s tax and Class 4 National Insurance liability was at least £1,000, unless more than 80% of the tax was collected at source, such as through PAYE.

The two Payments on Account are normally:

• 31 January during the tax year
• 31 July after the end of the tax year

Each payment is normally 50% of the previous year’s relevant liability.

Any remaining balance is then paid by the following 31 January.

What is changing from April 2029?

From 6 April 2029, Self Assessment taxpayers who also have sufficient PAYE income will be required to pay more of their forecast Self Assessment liability during the year through PAYE.

Instead of waiting for the usual Self Assessment payment dates, HMRC intends to collect the relevant amount through the taxpayer’s salary or pension payments.

The amount will be based on the taxpayer’s forecast liability, using information such as their most recent Self Assessment return.

For someone with regular income, this could mean their Self Assessment tax is spread across their normal pay periods rather than building up into a large bill later.

HMRC has said that the change is about when tax is paid, rather than increasing the amount of tax due.

Example: how could this work?

Imagine someone is employed but also earns additional income from a property business or self-employment.

Under the current system, they may have to calculate their Self Assessment liability and pay it through the normal Self Assessment payment dates.

Under the new arrangements, where they have sufficient PAYE income, HMRC will use their forecast Self Assessment liability and collect payments through PAYE during the year.

The taxpayer would still complete their Self Assessment tax return as normal.

If the final liability is different from the forecast, the position would be reconciled after the tax return is submitted. The taxpayer could then have a balancing payment to make or be entitled to a refund.

What about taxpayers without PAYE income?

This is where things are still being explored.

HMRC is considering whether taxpayers who do not have enough PAYE income should also make their Self Assessment payments more regularly.

One proposal is to increase the frequency of Payments on Account and bring those payments forward so they are made during the same tax year as the income is earned.

Under the proposal, payments could be based on a forecast of the taxpayer’s liability, using previous tax returns as a starting point.

Once the taxpayer submits their tax return, HMRC could reconcile the forecast payments against the actual liability.

If too little tax had been paid, a balancing payment could be required. If too much had been paid, the taxpayer could receive a refund.

However, no final decision has yet been made on wider changes for taxpayers who have only Self Assessment income.

Why is HMRC looking at more frequent payments?

One of the main reasons is to reduce the size of unexpected tax bills.

HMRC says that some Self Assessment taxpayers can currently face a significant gap between receiving income and paying the related tax. This can make budgeting more difficult and may contribute to tax debt.

HMRC’s June 2026 factsheet states that around one in five Self Assessment tax bills are paid late.

Spreading payments throughout the year could make tax bills easier for some taxpayers to plan for.

However, taxpayers with seasonal or fluctuating income may need additional flexibility because their income may not be consistent throughout the year.

What happens to the Self Assessment tax return?

The introduction of more timely payments does not remove the requirement to file a Self Assessment tax return.

Taxpayers will still need to report their income and expenses and complete their return.

The final tax position will then be compared with the payments already made during the year.

If the forecast was too low, there may be additional tax to pay.

If the forecast was too high, the taxpayer could be due a repayment.

The transition period could be important

Moving from the current system to in-year payments could create a cash-flow challenge.

During the transition, taxpayers may have to deal with payments relating to the previous tax year while also making payments towards the current year’s forecast liability.

For example, someone moving into the new system from April 2029 could still have outstanding payments under the existing arrangements for the 2028/29 tax year, while beginning to make payments towards their 2029/30 liability.

HMRC has recognised this issue and is considering ways to make the transition easier.

Possible options include allowing previous-year liabilities to be spread over a longer period or allowing taxpayers to make voluntary advance payments before the new system begins.

What should Self Assessment taxpayers do now?

There is no need to change your Self Assessment payment arrangements today solely because of these proposals.

However, it is worth preparing for a system where tax payments may happen more regularly.

A few practical steps can help:

1. Keep your records up to date

Accurate records of income and expenses will make it easier to estimate your tax liability.

2. Monitor your income during the year

If your income changes significantly, your forecast tax liability may also change.

3. Plan for the 2029 transition

If you currently rely on the January and July payment dates, consider how a move towards in-year payments could affect your cash flow.

4. Don’t ignore your Self Assessment return

Even with more frequent payments, you will still need to submit your tax return and reconcile your final liability.

5. Take advice if your income fluctuates

Self-employed individuals, landlords and people with several income sources may need to pay particular attention to how forecast payments could work for them.

Frequently Asked Questions (FAQs)

1. Will I pay more tax from April 2029?

Not simply because of the change in payment timing. HMRC states that the reform is intended to change when Self Assessment tax is paid rather than increase the underlying tax liability.

2. When will the new PAYE collection system start?

The announced change is due to take effect from 6 April 2029, the start of the 2029/30 tax year.

3. Will everyone in Self Assessment pay tax through PAYE?

No. The confirmed reform applies to Self Assessment taxpayers who have sufficient PAYE income. HMRC is separately exploring options for taxpayers without sufficient PAYE income.

4. Will I still need to file a Self Assessment tax return?

Yes. The new payment arrangements do not remove the requirement to complete a Self Assessment return where one is required.

5. What happens if my actual income is different from HMRC’s forecast?

The forecast payments would be reconciled against the actual liability when the tax return is submitted. Depending on the difference, you may have a balancing payment to make or be entitled to a refund.

Final thoughts

The move towards more timely Self Assessment payments could change the way many UK taxpayers manage their tax bills.

From 6 April 2029, taxpayers with Self Assessment income and sufficient PAYE income will be required to pay more of their forecast Self Assessment liability through PAYE during the year.

For taxpayers without sufficient PAYE income, HMRC is still exploring options for making Payments on Account more frequent and closer to the time income is earned.

The key point is that the proposed reforms are mainly about changing the timing of tax payments, not increasing the overall tax liability.

As the consultation process continues, taxpayers and uk tax advisers should keep an eye on HMRC’s final guidance, particularly around the transition arrangements and the treatment of fluctuating income.

Disclaimer: This article is for general information only and reflects the HMRC proposals and announcements available in September 2026. The final rules and implementation details may change. Taxpayers should check the latest HMRC guidance or seek professional tax advice for their individual circumstances.