FIRECalc and Tips

[MJ]

I have been very pleased with FIRECalc but as I get closer to ERing (5 to 6 months away), I am beginning to question some of the calculations.
Being conservative, I had planned to keep 75% to 80% of my assests in Tips. The results has always given me 100% survival but I questioned how much money I really would have available, the 1st 10 years of my ER.
I decided to enter a what if scenario, I removed SS and any future expense reductions

Starting portfolio 1,000,000
Lifespan of Portfolio 40
SS 0
Withdrawal 1 & 2 0
Stocks in portfolio 0
Tips @ 2.5
Expenses 0
Inflation PPI

The maximum SWR was calculated @ $26,900.

1) During the 1st 10 years, I would only get $25,000.
2) Assuming that the inflation was at 3% for the 1st 10 years, I would be paying taxes on the additional $30,000 (3% of principal).
$55,000 ($25K + $30K)
$10,000 (tax deductions)
$45,000 (taxable)
$ 7,650 (US and state tax about 17%)

That would leave me with approx. $17,350 (after taxes).

Am I missing something?

MJ