Income tax, Social Security, and mandated disability insurance are deductible
Mandatory levies on income — income tax, Social Security, government-mandated disability insurance — are deducted before maaser, since that money never becomes yours. Note: a tax refund or credit you receive is new maaser income.
Positions by community
Ashkenazi
R' Moshe Feinstein (Igros Moshe YD 1:143): income tax taken from one's earnings by government mandate is not considered income; maaser is computed on post-tax net income. He also rules one may keep the tax-credit benefit generated by charitable deductions, though the resulting higher net income is itself subject to maaser (AskTheRav).
Sephardi
Commonly follows the same net-of-income-tax calculation.
Chabad
AskTheRav (Chabad) rules the same: maaser is 10% of net income after income tax, with tax credits from donations added back to income.
Sources
- https://asktherav.com/2351-what-is-the-proper-way-to-calculate-maaser-and-taxes/ — Yoreh De'ah vol. 1, siman 143
- https://outorah.org/p/51498/ — Pre-Maaser Deductions (note: OU prints '1:43', a typo for 1:143)
- https://www.halachafortoday.com/ma-aser — Hilchos Maaser Kesafim archives
Track this for yourself
Tag transactions against rules like this one and see your running maaser balance.
MyMaaser presents sourced halachic positions and is not a substitute for your rav. Consult your rav (CYLOR).