We give away at least 10% of post tax income each year and many years it’s over 10% of pre-tax income. Slightly more than 10% (post-tax) comes out of our main account each month by DD into a separate ‘tithing’ account, which we use for regular support of various charities and our church. We also use that account for some one-off charitable donations.
However at least once a year we give larger amounts from our main account to charities as the need arises - eg a couple of thousand to the DEC, a similar amount to a charity which had a specific appeal etc.
For us, keeping the money separate means we don’t miss it, and although we are now very comfortable financially, we’ve done this for years, including individually before we were married and had far less income. We’re following the teaching of the Bible, but also what was modelled to us, particularly by my parents, who give generously in time, money and resources despite having less income.
If we didn’t do this, of course we’d have more disposable income, but actually the mindset is more valuable to me - material possessions don’t bring happiness, everything we have is God’s and we are to be wise stewards.
This doesn’t mean we live a miserly existence, we have a nice house, go on holidays etc, but our mortgage is very small compared to our income level, we don’t spend lots on new cars etc. we don’t buy our kids (or ourselves) the latest iPhone.
I’m realising this is all sounding a bit smug, and I really don’t mean it to, I’m trying to say that living generously, holding material possessions lightly, while not always easy, brings contentment. That’s why the Bible commands it.