Key Deadlines 2018/19

Payment deadlines

Self assessment2018/192017/18
1st payment on account31 January20192018
2nd payment on account31 July20192018
Balancing payment31 January20202019
Capital Gains Tax31 January20202019
National insurance
Class 1A NIC19 July20192018
Class 1B NIC19 October20192018


  1. Payments on account for 2018/19 are based on 2017/18 self assessed Income Tax, Class 2 NIC and Class 4 NIC.
  2. Non-residents with gains on UK residential property must pay CGT within 30 days of disposal, unless already filing a self assessment tax return.
  3. Missing any payment dates leads to interest being charged at 3%.
  4. Missing the balancing payment date by 30 days will lead to a 5% penalty.
  5. When the balancing payment is 6 and 12 months late, further 5% penalties apply on each occasion.
  6. Employment income is charged to both Income Tax and to Class 1 NIC.
  7. Tax and NIC are normally paid by the employer through the PAYE system, under which the PAYE code makes adjustments for tax reliefs due and some tax due on other income.
  8. Where a payment date is the 19th of the month, any cheque must reach HMRC by that date, or the business day preceding it (if the 19th falls on a week-end or Bank Holiday). Online payments can reach HMRC by 22nd of the month without incurring interest.
  9. An employee who has overpaid or underpaid tax at the end of the year will normally receive a tax calculation from HMRC on form P800 and shortly afterwards receive a tax repayment, or be asked to pay any tax due.
  10. If the tax underpaid is no more than £3,000, the underpayment can be settled through PAYE in the following tax year.

Filing deadlines

For tax year2017/18
Issue P60s to employees31 May 2018
P11D and P11D(b)6 July 2018
Paper version of self-assessment return31 October 2018
Online self-assessment return31 January 2019


  1. Where taxpayers submit the 2017/18 self assessment tax return by 30 December 2018, they can request that underpaid tax, within limits, is collected through PAYE code in the following tax year.
  2. A late filing penalty of £100 will be issued if the self assessment return is not submitted within the deadlines indicated above. This applies even if no tax is due.
  3. Further late filing penalties are due if the self assessment return is more than 3, 6 and 12 months late.