Terry's salary is taking home $$52,000$ and gross $$76,000.$ Evelyn is $$29,000$ and $$42,000$ respectively. They had $2016$ capital gains of $(5,500$ loss$),$ interest income of $4,000,$ investement retirement account IRA contributions of $5,000,$ the standard deduction is $12,400,$ dependency deduction is $3,950.$ Investments returns SP$500$ ETF $($stocks$)$ can earn $9\%.$ TBILLS ETF $($bonds$)$ can earn $3\%.$ Capital gains are taxed at $10\%,$ fixed income is taxed at $15\%,$ and estate taxes are $30\%$

The question is: What would be the new taxable income if they decide to contribute to the IRA double the actual amount. How much are they going to accumulate after taxes at the age of $65,$ assuming $80\%/20\%$ stocks bonds portfolio