The effort to reconcile data of aggregate revenue collection between revenue board and Controller General of Accounts (CGA) faced a blow due to flaws in the accounts system, known as 'iBAS++'.
Officials said the National Board of Revenue (NBR) could not cross-check the revenue collection figure for fiscal year 2018-19 as the CGA office stopped sending the monthly data of the July 01 to June 30 period.
They said due to flaws in the iBAS++ system, errors have crept up in the source report.
The NBR published the aggregate tax revenue collection data for FY 2018-19 worth Tk 2.23 trillion on the basis of conservative calculation from its field-level tax offices.
On several occasions, economists, think tanks and policy makers criticised the mismatch between the data compiled by the NBR and CGA office.
An inter-ministerial committee, comprising officers of the NBR research cell and CGA office, was formed in April last year to reconcile the tax revenue collection figure before making it public.
A member of the committee said the NBR did not get any of the tax collection data of the last fiscal, despite several communications.
In FY 2017-18, the mismatch between the NBR and CGA data was Tk 144 billion. The NBR recorded a revenue collection of Tk 2.02 trillion while the CGA found it Tk 1.87 trillion.
A senior NBR official said the tax authority has detected a number of inconsistencies in analysing the revenue collection data by the CGA office.
In a letter, the research wing of the board has drawn the attention of the Chief Accounts Officer spotting seven key inconsistencies.
The NBR has detected a major mismatch between the provisional and final data of the CGA office for FY 2017-18 on the areas, where names of the relevant departments are not mentioned.
The revenue board has found mismatch worth Tk 114.93 billion between the CGA offices provisional and final data of revenue collection by the Chittagong custom house on account of VAT and customs duty on import stage.
"The NBR could not detect the reason for inconsistencies due to the absence of names of the revenue collecting source office," the NBR letter said.
It has also found iBAS++ has not counted the import stage VAT collection data worth Tk 11.97 billion by Benapole customs house.
The NBR has found the tendency of depositing the import stage VAT in the wrong code by Sonali Bank.
Some government organisations that maintain their own accounts such as Railway and Roads and Highway deposit the revenue to the public exchequers, which were not reflected in the CGA data, officials said.
The NBR found that VAT worth Tk 3.98 billion was deducted at source by the railway ministry's project, but that was missing in the CGA revenue collection data.
Addressing the problems of iBAS++, the CGA office took initiative to resolve it seeking help from the government's relevant agencies.
The CGA office sent letters twice to the director of the Public Expenditure Management Strengthening (PMES) Programme to amend the revenue collection report in the iBAS++ system.
It found errors in the source report of revenue collection figure of different offices under NBR for FY 2018-19.
In the letter, the CGA office said in the iBAS++, there is no typing option of transaction in the book transfer entry of the Duty Exemption and Drawback Office (DEDO) and Dhaka Customs House.
The CGA office is facing difficulties to include the revenue collection data, which are received through drawback cheque and credit note.
A senior NBR official said tax, VAT and customs commissioners do not have access to the iBAS++ system to check the real time depository of revenue of the CGA office.
The revenue board also does not get tax collection data regularly from the CGA office to reconcile the figure before making it public, he added.
NBR officials have found that CGA officials remained absent in most of the meeting of the inter-ministerial committee, which is empowered to reconcile revenue collection figure.