Nigeria could be facing a fiscal crisis if it doesn't improve its ability to collect taxes, the authorities have warned.
Government expenditure has doubled and debt servicing costs have grown, but revenues have missed their targets by at least 45% a year since 2015.
Despite that, the Nigerian president's office has praised the work of the national tax body, the Federal Inland Revenue Service (FIRS), for doubling the number of taxpayers since 2015.
It is noteworthy and highly commendable that under this administration, the number of taxable adults has increased from 10 million to 20 million with concerted efforts still on-going to bring a lot more into the tax net. //— Presidency Nigeria (@NGRPresident) August 19, 2019
Some online users were quick to ask if that's true, why hasn't there been an equivalent increase in government revenue, and as a result improvements in things like schools, roads and healthcare?
Getting more people to pay tax
In 2018, 19 million Nigerians paid into federal or state coffers, according to government data.
A World Bank report in that year put the country's economically active population at 65 million - so even with rising numbers of taxpayers in recent years, that is still less than 30% paying tax.
The government has been going after individuals that it believes are liable for tax and have not been paying.
Two years ago, the country offered a 12-month amnesty for Nigerians to declare and pay taxes on all previously undeclared income and assets to avoid penalty payments and possible prosecution.
A World Bank report last year said this was only partly successful with just 8% of the target achieved by the end of the amnesty period.
However, many Nigerians will be reluctant to pay taxes because of concerns the money raised may be siphoned off instead of being spent on health, education and other public services.
Oil price goes down
The big issue facing the government has been lower international oil prices and the recession experienced by the Nigerian economy in 2016.
The average price of crude oil fell from around $113 a barrel in 2012 to just over $54 in 2017.
Nigeria is Africa's largest oil producer and between 2012 to 2014, the oil sector provided 57% of total government revenue. This fell to 41% between 2016 to 2018.
The government says that value added tax (VAT) and company income tax have been on the increase since 2015.
Nigeria also says it is intensifying measures to collect tax from new revenue streams, such as online transactions. It has said it will ask banks to charge tax at 5% on online transactions, both domestic and international, from January 2020.
A report this year by Oxford University's Oxford Martin School estimates that non-oil revenues have risen but adds that much of the gain has been wiped out by inflation and currency movements.
How does it compare globally?
According to some estimates, Nigeria has one of the world's lowest ratios of tax to GDP.
That is the total amount of tax collected as a proportion of GDP - the value of the country's goods and services.
In 2016, it was at 6%, going by figures from the Organisation for Economic Co-operation and Development (OECD), a grouping of the world's leading market economies.
That is the latest year for which data is available.
The tax-to-GDP ratio in South Africa was 29%, Ghana 18%, Egypt 15% and Kenya 18%, says the OECD.
The average for OECD members - which includes all the advanced economies - was 34%.
The World Bank uses a slightly different measurement of tax take, which does not include most social security payments.
This puts Nigeria's tax-to-GDP ratio in 2016 lower at just 3.4%.
In 2017, the ratio did improve to 4.8%, according to figures provided to us by the Nigerian authorities.
We don't have a figure for 2018, but it is worth pointing out that 15% is the level which the World Bank says is necessary to achieve economic growth and poverty reduction.
How do you improve tax take?
Many other developing countries have a low tax-to-GDP ratio and recent data indicates that about 60 countries fall below the 15% threshold.
Bernardin Akitoby, an assistant director in the IMF, says a typical advanced country has a tax to GDP ratio of around 40%.
Mr Akitoby says there is no one-size-fits-all solution to increase the tax take - but there are a few lessons that can be drawn from countries that have been successful in the past:
- a clear political mandate to tackle low levels of tax payment
- a simpler tax system with a limited number of rates and exemptions
- using taxes on goods and services
- boosting tax collection by using new technology