By 1989 the 1981 statutory floor of ₦125/month had been eroded by Structural Adjustment, two naira devaluations and the abolition of the import-licence regime to roughly ₦25 in 1981 purchasing power. The Nigeria Labour Congress, under Ali Chiroma, served a strike notice in March 1990 demanding ₦500/month. The Babangida regime — politically vulnerable after the May 1989 anti-SAP riots and the April 1990 Orkar coup attempt — passed the National Minimum Wage (Amendment) Decree No. 18 of 1990, raising the statutory floor to ₦250/month for federal workers and large private employers, effective 1 January 1991.
A second amendment, the National Minimum Wage (Amendment) Decree No. 29 of 1993, raised the floor to ₦363/month in the dying days of the IBB regime, partly to buy industrial peace ahead of the 12 June 1993 election. Neither rate was implemented uniformly by state governments — most northern states paid arrears years late, several never paid in full — and neither survived the 1994–1998 inflation under Abacha, when the naira fell from ₦22 to over ₦80 against the US dollar and the real value of the ₦363 wage collapsed to under ₦80 in 1990 terms.
The 1990 and 1993 amendments are remembered less for their nominal value than for two structural shifts: they entrenched the 50-employee threshold (preserving the exemption of small employers and agriculture inherited from 1981), and they made plain that state governors could quietly refuse to implement a federal wage and face no sanction. Both pathologies persisted into the 2000 Obasanjo settlement and remain live politics today.