On taxes, you can deduct charitable giving from the amount of income used to figure your federal taxes if you "itemize." The alternative to itemizing is claiming the standard deduction, which in 2025 is $15,000. That means that, as a practical matter, the first $15,000 in itemized expenses don't help you on your taxes, but anything over that does. A very general explanation of itemizing is here.
Major categories of itemized deductions include state/local taxes (capped at $10K), mortgage interest, and charitable giving. I'm not from California, but it looks like your state/local taxes may be ~$7K based on your income. That means that, as a practical matter, the first ~$8K you donate in a year may not help you on your taxes, but everything after that will. The usual (partial) workaround is to save up your donations in a separate account and donate them every few years for more favorable tax treatment. That's what my wife and I do.
I believe most people consider the amount of their income on a post-tax basis to the extent that their donations are not tax-deductible. For you, that would involve considering some taxes (e.g., Social Security/Medicare, maybe state) and part of your federal tax.
You're absolutely right that the pledge doesn't adjust for personal circumstances, cost of living, and other factors. In my opinion, it's overdemanding for some people, and underdemanding for others. I would consider 10% as both a community norm and as the specific ask of GWWC's flagship pledge. I think GWWC would primarily explain the use of a flat percentage ask as based on something other than it being the fairest / most philosophically sound ask in an ideal world.
I'll talk here about the community norm, which is more flexible than the pledge. As to specific factors:
- The cost of living is often somewhat reflected in the amount one earns -- you're in less of a position to give than someone who earned $120K/year in Peoria, but you probably wouldn't be making $120K/year in Peoria either. However, a flat percentage approach probably places a heavier burden on people in very high COL areas.
By definition, most people have fairly typical personal circumstances on net, with some factors enabling a higher donation percentage and others inhibiting it. Some have significantly more challenging circumstances than average and some have significantly more favorable circumstances than average. It sounds like you have some factors that are relatively favorable (e.g., no kids, some family support, developed country, relatively high income by US standards) and some factors that go in the opposite direction (e.g., very high COL area, just starting out). I think it's best to read the community norm as commending 10% to people in fairly typical personal circumstances, with the understanding that this may not be reasonable for people in less-than-average personal circumstances.
Just to address some of the valid points you raise:
(1) On charity effectiveness: At least in global health & development, GiveWell is considered the gold standard, and they are extremely rigorous in their evaluations - whether in terms looking at the scientific evidence or consulting experts or surveying beneficiaries or crunching the numbers in cost-effectiveness analysis or monitoring and evaluation.
I strongly suggest taking a look at their intervention reports (e.g. on mosquito nets to combat malaria: (https://www.givewell.org/international/technical/programs/insecticide-treated-nets) and their CEAs (https://docs.google.com/spreadsheets/d/18ROI6dRdKsNfXg5gIyBa1_7eYOjowfbw5n65zkrLnvc/edit?gid=1364064522#gid=1364064522), to see just how meticulous and thorough they are, and to judge whether they take into account the concerns you have on corruption etc.
To provide some examples of what GiveWell adjust for, in their typically obsessive way - they adjust for (i) risk of wastage from double treatment/ineffective goods/goods purchased and left in storage till expiry, (ii) risk of misappropriation and of false monitoring, (iii) risk in the charity changing priorities or having non-funding bottlenecks or funging funding between more vs less effective programmes; (iv) % of mosquito nets actually used, (v) coverage years lost due to use of residual nets from previous distributions, (vi) program not having impact because it simply moved distributions closer together, (vii) internal & external validity issues with the randomized control trails used as evidence etc.
(2) On giving now vs later. I think it generally comes down to the following considerations.
(a) Value drift: I do think it's a real risk that by not donating, you lose the motivation to do so (it's easy to come up with excuses to put it off, not unlike exercise or dieting or quitting smoking/drugs/alcohol etc) and just end up not giving at all.
(b) Reduced cost-effectiveness over time: For most top GHD interventions available to the public, their cost-effectiveness will decline over time, because economic growth makes countries richer and reduces poverty and disease burdens over time - so if you give later, some of the cheapest ways of saving lives or reducing poverty will no longer exist (e.g. think of how expensive it is to save a life in America vs in the Congo, as an extreme example).
(c) Interest rates - as you point out, saving allows for your donation pool to grow (whether you invest in stocks or bonds or whatever).
Overall, (a) + (b) probably outweigh (c), making it more optimal to give now rather than later.
Point (c) regarding interest rates is quite tricky & subtle. At least, you should probably take into account something like the real interest rate instead of the nominal rate, because ceteris paribus it's much more plausible that only real (ie inflation adjusted) growth of your donation pool matters.
I would go even further and claim that, in expectation, you need to outperform the real risk free rate in order to generate a net benefit by donating later.
This means that unless you're happy to take some investment risk and aim to ouperform in real terms point (c) doesn't matter much.
However, imo if you're at an early point in your career, investing in your future career flexibility by having savings can have extremely high returns, which can outweigh all the other points.