My tax rate in retirement is low enough that I actually just ignore it in Firecalc, but I think many people include a provision for taxes in their expenses rather than reduce their assets for taxes.
25% is probably way too much. What I would suggest is that you do a pro forma tax return using your retirement income (SS, pensions, estimated interest and dividends on retirement accounts, HSA contributions, deductions, etc. as applicable) to get a more realistic sense of what your tax rate will be in retirement. In my case it was as easy as taking the tax return for the last year i worked and zeroing out my earnings and making a couple other adjustments. Income Tax Calculator - Tax-Rates.org
is a handy calculator that covers both federal and state income taxes.
As an example, I went from around 25% (federal and state income taxes/income) the last year that I worked to a little over 2% last year, but I'm not yet drawing from tax-deferred accounts. Even if I was drawing from tax deferred accounts my federal and state income tax rate would only be ~11%, still substantially less than when I was working. The lower taxes (and especially 0% LTCG taxes) was one of the pleasant surprises of retiring.
Once you have a sense as to what your annual taxes will be you can do one of either two things. Add the taxes to your expenses (I suspect this is the most popular way to adjust for taxes) or tax your portfolio multiplied by (1-t) and ignore taxes in your expenses.