Contributions to your TSP account come right out of your paycheck. Each year the IRS sets the limit a service member can defer from their paychecks--it applies to both Traditional and Roth TSP accounts. This includes your basic pay, special pay and bonuses. To max out your TSP under the current contribution limit ($18,500 for 2018) you would need to contribute about $1,500 per month from your pay checks. That is very aggressive, but it is certainly possible, depending on your rank, pay grade and living expenses. It is important to note, DoD automatic and matching contributions are in addition to the annual elective deferral limit.