Self-assessment taxpayers owe HMRC more than £1.6 billion in late payments relating to their 2017/18 tax bills.
The deadline for 2017/18 submissions came and went on 31 January 2019, with more than 11.5 million taxpayers beating the midnight cut-off.
Despite a record number of tax returns submitted early this year, not all taxpayers have paid their liabilities to the Revenue.
The £1.6bn owed for 2017/18 is expected to surpass the £1.83bn paid late in 2016/17.
A spokesperson for HMRC said:
"We want people to pay on time rather than receive penalties.
"If customers are unable to pay on time, they may avoid penalties by contacting us as soon as possible and we can discuss whether it might be possible to set up a payment plan."
In January 2018, the Revenue banned taxpayers from using their personal credit cards to pay their annual tax bills.
Personal debit cards can still be used to pay a tax bill, however, as can company or corporate credit cards.
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