The figure is above the monthly average of late paid taxes over the last year at £4.39bn.
Sean Glancy, partner at UHY Hacker Young, said: “If HMRC added £5bn of late paid taxes to its systems in March then just think how much could be added in April and May.”
He said more businesses and individuals are “being forced” to delay tax payments and with an “economic rebound still uncertain” the trend will continue.
Glancy said: “Levels of overdue tax are going to get much worse as we head into summer and Autumn.The VAT deferment period ends on June 30 and from that date businesses will have to start paying VAT again, which could lead to a spike in overdue taxes.
“HMRC has done a lot to help businesses. From the end of June, HMRC has promised to be more lenient in accepting businesses who apply to enter into arrangements that restructure tax payments ,but this would also lead to more overdue tax.”
UHY Hacker Young reported there were already 647,770 taxpayers in ‘Time To Pay’ arrangements in March this year.
The recent surge in tax scams has reportedly emerged from criminals seeking to “exploit financial fears over the coronavirus outbreak”, the paper has alleged.
It comes as a recent freedom of information (FOI) request revealed that the number of phishing emails reported to HMRC reached 42,575 in March, marking a 74% rise since January, when 24,446 phishing emails were reported.