Here are seven of the bigger scandals that happened (or continued) under President Mahama's watch.
Sole-sourcing and inflating contracts
There have been a number of accusations of corruption under Mahama's NDC leadership relating to Government contracts awarded to President Mahama's brother Ibrihim Mahama, as well as over-inflating costs on contracts. NPP have alleged the pair were connected to the almost $600 million dollar Ameri Power deal.
Two Norwegian investigative journalists alleged a fraudulent deal on 10 power turbines from Ameri Group of Dubai, after the NDC Government entered into a Built, Operate, Own and Transfer agreement with Ameri Energy of Dubai for the supply of 10 turbines with 230-250MW capacity of power. There was strong accusations the project was costed at a lot more than it was worth – experts said the turbines should cost $220 million, asking where the extra $360 million was meant to go.
"Overpricing of contracts, through the use of sole sourcing, is a corrupt procurement method of choice very typical of the Mahama-led NDC government," the NPP said in its 2016 manifesto.
Smartty's Bus branding saga
News headlines in late 2015 were dominated by the Smarttys bus branding scandal, where 116 Metro Mass Transit (MMT) buses were rebranded at a cost of GH¢3.6 million.
The cost for rebranding these buses was seen as ludacris and the Attorney General got involved, demanding refunds be made. The outcry lead to the resignation of the Minister of Transport, Ms Dzifa Attivor, in December.
Also under the NDC was the 2013 GYEEDA scandal, uncovered by Joy FM's Manasseh Azure Awuni, whose investigation led to policy change in the running of the agency. The reporter found millions of cedis were paid illegally to contractors of the Ghana Youth Employment and Entrepreneurial Agency (GYEEDA).
When President Mahama was made aware of the corruption he instructed the Attorney-General and Minister of Justice to retrieve the money illegally paid to individuals and companies through contracts with GYEEDA, the Savanna Accelerated Development Agency (SADA) and the Ghana Revenue Authority (GRA).
He had also asked the Minister for Youth and Sports to suspend, with immediate effect, all payments under all GYEEDA contracts, except the payment of arrears to workers up to the end of the year.
The government set up a five-member committee to probe the allegations further. The committee’s report largely corroborated Manasseh’s findings and made various recommendations to government. As part of the reforms, parliament passed a law to regulate the operations of GYEEDA, which was later renamed Youth Employment Agency (YEA).
The investigations showed that SADA paid GH₵32,498,000 to ACICL to plant five million trees in the savannah zone, but could only account for about 700,000 trees.
It also found that SADA spent GH¢15 million on guinea fowls, but could only account for a few of the birds.
President Mahama caused outrage across Ghana when it was revealed he accepted a gift of a Ford vehicle from a construction firm bidding for a lucrative government contract. The contractor in Burkina Faso, who had previously built a wall on Ghanaian Embassy land in Ouagadougou, gifted the Ford in 2012. However, this scandal came out in 2016.
NPP said the gift was a bribe to get a road-building contract in Ghana's Volta region that the same contractor later secured.
Mahama himself called the accusations "baseless". The vehicle was a gift and had been added to the government car pool.
Mahama was cleared of the corruption allegations by the Commission on Human Rights and Administrative Justice (CHRAJ) which said in a 78-page report that a claim of conflict of interest against Mahama "has not been substantiated". However it did find Mahama guilty of breaching government rules on the acceptance of gifts.
2015 was defined by investigative journalist Anas Aremeyaw Anas' allegations into widespread corruption in the judiciary. His undercover reporting in the film Ghana in the eyes of God; Epic of Injustice. His findings were global - shaking Ghana's reputation.
Anas collected evidence of a range of Ghana judges allegedly taking bribes and demanding sexual favours in return for throwing cases.
Some 22 lower court judges and 12 High Court judges were captured on video in a two-year investigative piece Anas, allegedly taking bribes to influence justice.
So far, 20 of the lower court judges have been removed from office and three high court judges.
A name dominating the headlines in Ghana the past few years is Alfred Agbesi Woyome, accused of swindling the taxpayers of Ghana of millions. As explained by Ghanaian journalist, Manasseh Azure Awuni, the Government of the National Democratic Congress (NDC) under President John Evans Atta-Mills, fraudulently paid a financier of the party GHc 51.2 million cedis between 2010 and 2011. A Supreme Court Judge, Justice Jones Dotse said it appeared those who facilitated the payment “entered into an alliance to create, loot and share the resources of this country as if a brigade had been set up for such an enterprise”.
Martin Amidu, former Minister of Justice and Attorney-General has taken on the case determined to retrieve the money fraudulently paid to Woyome. In July 2014 the Supreme Court ordered Woyome to pay the money back to the state, but the businessman did not do that.
The state pursued the criminal aspect of the case but lost. It appealed and lost again. Government officials argued that Woyome received the money legitimately.
The Attorney-General has also filed to discontinue the case, meaning she was no longer interested in examining Woyome in court. This month, the Supreme Court adjourned the case indefinitely.
Perhaps not surprisingly, the Global Corruption Barometer report on Ghana by the Transparency International (TI), 2015 showed that statistics indicate that more than 50% of the respondents perceived that corruption has increased and significant 35% think it is extreme.
Among the different institutions, respondents perceived the following institutions as extremely corrupt; Police (92%), Judiciary (71%), political parties (76%) and public officials and civil service (59%).
TI also found that 57% of the respondents also indicated that they or a member of their household have paid a bribe to one of these public institutions.