If you do 20 years AD service under BRS, will you begin receiving your pension as soon as you ETS?

If your question is do you get a pension check at the end of 20 years under BRS, the answer is yes. The difference is that you only get 2% per year credit for pay based on your high three years. So you basically will get 40% of your top three years instead of 50% under a traditional retirement. Hopefully you took advantage of the savings option too.

"Lump Sum Option
When you retire ( or at age 60 for guard/reserve members), you will be given the option to receive monthly retirement pay checks, or you can take a lump-sum payment of either 25% or 50% of your gross estimated retired pay, and get smaller monthly checks.

If you take a 25% lump-sum payment, your monthly retirement pay will be 75% of the normal full retirement pay. If you take the 50% lump-sum, it will be 50% of the normal retirement pay."

"Also, your lump-sum payment is discounted by an amount that changes every year. For 2020 this discount rate is 6.75%. That means that if your total retirement is determined by your finance office to be $100,000 you would only receive $93,250 (100,000 discounted by 6.75%). Also, the lump sum payment is taxable.

When you reach age 67 your retirement pay goes back up to the full amount if you take either lump-sum option."

More info here: https://www.military.com/benefits/military-pay/blended-retirement-system.html#:~:text=The%20Blended%20Retirement%20System%20Summed%20Up&text=Defined%20Benefit%3A,of%20your%20final%20base%20pay.

https://militarypay.defense.gov/blendedretirement/

https://www.militaryonesource.mil/financial-legal/personal-finance/retirement-planning/frequently-asked-questions-regarding-the-new-blended-retirement-system/

You'll definitely want to be maxing those matching contributions the whole time in order to get the most out of the BRS.