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Isabel, a calendar-year taxpayer, uses the cash method of acounting for her sole proprietorship. in late December she received a $21,000 bili from her accountant for consulting services related to her small business. Isabel can pay the $21,000 bill anytime before January 30 of next year without penalty. Assume her marginal tox rate is 37 percent this year and next year, and that she can earn an after-tax rate of relurn of 4 percent on her investments. a. What is the after-tax cost if Isabel pays the $21,000 bill in December? b. What is the after tax cost if Isabel pays the $21,000 bill in January? Use Exhilbit 31 (Round your answer to the nearest whole dollar omount.) c. Based on requirements a and b, should isabel pay the $21,000 bill in December or January? EXHIBIT 3-1 Present Value of a Single Payment at Various Annual Rates of Return \begin{tabular}{|l|c|c|c|c|c|c|c|c|c|} \hline & 4% & 5% & 6% & 7% & 8% & 9% & 10% & 11% & 12% \\ \hline Year 1 & .962 & .952 & .943 & .935 & .926 & .917 & .909 & .901 & .893 \\ \hline Year 2 & .925 & .907 & .890 & .873 & .857 & .842 & .826 & .812 & .797 \\ \hline Year 3 & .889 & .864 & .840 & .816 & .794 & .772 & .751 & .731 & .712 \\ \hline Year 4 & .855 & .823 & .792 & .763 & .735 & .708 & .683 & .659 & .636 \\ \hline Year 5 & .822 & .784 & .747 & .713 & .681 & .650 & .621 & .593 & .567 \\ \hline Year 6 & .790 & .746 & .705 & .666 & .630 & .596 & .564 & .535 & .507 \\ \hline Year 7 & .760 & .711 & .665 & .623 & .583 & .547 & .513 & .482 & .452 \\ \hline Year 8 & .731 & .677 & .627 & .582 & .540 & .502 & .467 & .434 & .404 \\ \hline Year 9 & .703 & .645 & .592 & .544 & .500 & .460 & .424 & .391 & .361 \\ \hline Year 10 & .676 & .614 & .558 & .508 & .463 & .422 & .386 & .352 & .322 \\ \hline Year 11 & .650 & .585 & .527 & .475 & .429 & .388 & .350 & .317 & .287 \\ \hline Year 12 & .625 & .557 & .497 & .444 & .397 & .356 & .319 & .286 & .257 \\ \hline Year 13 & .601 & .530 & .469 & .415 & .368 & .326 & .290 & .258 & .229 \\ \hline Year 14 & .577 & .505 & .442 & .388 & .340 & .299 & .263 & .232 & .205 \\ \hline Year 15 & .555 & .481 & .417 & .362 & .315 & .275 & .239 & .209 & .183 \\ \hline \end{tabular}