How does one calculate Maaser if they are receiving a 1099 at the end of the year for taxes? (In other words: they will be taking off more at the end of the year, so they should not have to give Maaser for that money.)
There are technically two options:
1. Although it is recommended for a number of reasons to separate Maaser as soon as one receives earnings, and some Poskim even regard this as a requirement, most Poskim hold that it is acceptable to make Maaser calculations and allocations for the entire year at once. He may choose any date of the year as the cut-off for accounting purposes. Therefore, you could choose to make your accounting each year on a date at which you should have a good idea of your tax liability.
2. Another option is to estimate your tax amount to the best of your ability, and allocate as Maaser only the funds that you are certain belong to Maaser. Then you can “balance the books” and pay any remainder once you have done your taxes.