You are mistaken. Tax receipts as a % of GDP went down (because GDP grew alot). Actual tax receipts went up 60%.
During the Reagan administration, federal receipts grew from $618 billion to $991 billion (an increase of 60%);
During the Reagan administration, the American economy went from a GDP growth of -0.3% in 1980 to 4.1% in 1988 (in constant 2005 dollars), averaging 3.4% annual growth in constant dollars. This reduced the unemployment rate by 1.6%, from 7.1% in 1980 to 5.5% in 1988
According to a 1996 report of the Joint Economic Committee of the United States Congress, during Reagan’s two terms, and through 1993, the top 10% of taxpayers paid an increased share of income taxes (not including payroll taxes) to the Federal government, while the lowest 50% of taxpayers paid a reduced share of income tax revenue.
The misery index, defined as the inflation rate added to the unemployment rate, shrank from 19.33 when he began his administration to 9.72 when he left, the greatest improvement record for a President since Harry S. Truman left office. In terms of American households, the percentage of total households making less than $10,000 a year (in real 2007 dollars) shrank from 8.8% in 1980 to 8.3% in 1988 while the percentage of households making over $75,000 went from 20.2% to 25.7% during that period, both signs of progress.
Real wages were lower following the recession, while real median family income grew by $4,000 during the Reagan period. But, using data of U.S. Bureau of Economic Analysis, real U.S. GDP in 2009-chained dollars divided by the U.S. population, shows that real per-capita GDP went from $26,196.55 in the 4th quarter of 1976 to $28,447.21 4th quarter of 1980, a real increase of 8.6% during President Carter’s four years. President Reagan’s eight years in office saw per-capita GDP grow another 23.4% to $35,097.83.
Only one big problem, they never cut spending.
Spending during the years Reagan budgeted (FY 1982–89) averaged 21.6% GDP, roughly tied with President Obama for the highest among any recent President. Each faced a severe recession early in their administration. In addition, the public debt rose from 26% GDP in 1980 to 41% GDP by 1988. In dollar terms, the public debt rose from $712 billion in 1980 to $2.052 trillion in 1988, a roughly three-fold increase.:143 The unemployment rate rose from 7% in 1980 to 11% in 1982, then declined to 5% in 1988. The inflation rate declined from 10% in 1980 to 4% in 1988.