Five deductions are available to all household types. 106 C.M.R. § 364.400. Households with an elder or person with a disability can seek the medical deduction and higher shelter deductions. See Question 53 (What medical expenses can I claim if I am elderly (60+) or disabled?).

The following deductions are allowed for all household types:

• 20 percent of gross earned income. 106 C.M.R. § 364.400(B).
• Self-employment business expenses. 106 C.M.R. § 365.940. See Question 46 (How is self-employment income counted?).
• A standard deduction based on household size: 106 C.M.R. § 364.400(A). Every SNAP household gets this standard deduction from countable income (current amounts, adjusted October 2011).

  $147	for households of 1-3 persons,
  $155	for households of 4 persons,
  $181	for households of 5 persons, and
  $208	for households of 6 or more persons.

• A child care or disabled adult care deduction if you are working, looking for work, or in school or training. You can claim the full amount you are responsible to pay for each child under age 18 and/or for the custodial care of an adult who is elderly or has a disability. 106 C.M.R. § 364.400(D). See Question 55 (What is the child care/dependent care deduction?) describing the range of allowable expenses.
• Child support paid to children outside the home (including payments for health insurance, child support arrearages, payments made to third parties for rent or mortgage) if you are legally obligated to pay the support for a child of yours who does not live with you, 106 C.M.R. § 364.400(E). See Question 54 (What is the child support deduction?).
• A shelter deduction capped at $459 for households that do not include an elder or a person with a disability. For households with elders or persons with disabilities, the shelter deduction is un-capped. 106 C.M.R. § 364.400(G). The shelter deduction is the amount by which your shelter expenses exceed one-half of your "preliminary net income," which is the result after subtracting the other deductions. See Questions 56 (What is the standard utility allowance (SUA) and what is H-EAT?) and 57 (What is the shelter deduction and how does DTA calculate it?) on how to calculate the shelter deduction.
  
  If you are homeless and have no rent or utility obligations, you get a homeless shelter deduction of $143 a month instead of the shelter deduction. 106 C.M.R. § 360.400(F). See Question 58 (What is the homeless shelter/utility deduction and who gets it?).

The result is your monthly net income. Your benefits are based on this amount. The following questions include examples of how the deductions work to reach net income.