Discretionary Spending

Function 050 - National Defense

Defer Development of the B-21 Bomber

CBO periodically issues a compendium of policy options (called Options for Reducing the Deficit) covering a broad range of issues, as well as separate reports that include options for changing federal tax and spending policies in particular areas. This option appears in one of those publications. The options are derived from many sources and reflect a range of possibilities. For each option, CBO presents an estimate of its effects on the budget but makes no recommendations. Inclusion or exclusion of any particular option does not imply an endorsement or rejection by CBO.

Billions of Dollars 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2019-
Change in Planned Defense Spending  
  Budget authority 0 -3.0 -3.1 -3.3 -4.1 -5.7 -7.7 -6.7 -5.9 -5.5 -13.5 -44.9
  Outlays 0 -1.5 -2.6 -2.7 -2.8 -3.4 -3.8 -4.5 -5.2 -5.4 -9.6 -31.8

This option would take effect in October 2019.
Estimates of savings displayed in the table are based on the 2019 Future Years Defense Program and the Congressional Budget Office's extension of that plan.


The Air Force operates a fleet of 157 long-range bombers: 76 B-52Hs, 61 B-1Bs, and 20 B-2A stealth bombers that entered service in the 1960s, 1980s, and 1990s, respectively. Although those aircraft should be able to continue flying through at least 2040, the Air Force is developing a new bomber—designated the B-21—which it plans to field in the mid- to late 2020s. The goal of that program is to produce at least 100 aircraft that could augment and eventually replace the B-1B and B-2A bombers. (The Air Force is developing plans for new engines and subsystems to extend the service life of the B-52H.) The Air Force has estimated that developing and procuring the first 100 aircraft will cost $80 billion (in 2016 dollars). The Congressional Budget Office has not assessed the validity of that estimate because many details about the program—including the B-21's speed, payload, and stealthy characteristics, as well as its production schedule—are classified.


This option would defer development of the B-21 bomber until after 2028.

Effects on the Budget

If implemented, this option would reduce budget authority by about $45 billion (in nominal dollars) through 2028, provided that appropriations were reduced accordingly. Those savings include $12 billion in research and development funding that the Air Force has budgeted for 2020 through 2023 (in its 2019 budget request), plus $33 billion through 2028 to complete development and begin procurement. To calculate those savings, CBO spread the Air Force's estimate of total costs for the program over a notional development and procurement schedule that would support initial fielding of B-21s by the mid- to late 2020s. Savings would differ if the Air Force's cost estimates proved to be inaccurate or if the fielding schedule changed, as often happens with programs that are developing new aircraft.

In terms of outlays, savings would be about $32 billion from 2020 through 2028. The remaining $13 billion reduction in outlays corresponding to the reduction in budget authority through 2028 would occur in later years. Reductions in outlays lag reductions in budget authority because the Department of Defense (DoD) pays for aircraft as expenses are incurred. For example, CBO projects that most of the outlays to procure new military aircraft would occur over four years to account for the time required to negotiate contracts, manufacture and deliver the aircraft, and process the final payments.

Shortening or lengthening the time over which the B-21 program was deferred would alter the projected savings. Additional savings might accrue after 2028 if DoD decided that it could accommodate a longer delay. Alternatively, a shorter deferment in developing and fielding the B-21 would yield lower savings.

Other Effects

An advantage of this option is that it would reduce acquisition costs at a time when the Air Force plans to modernize other parts of its fleet. Funding would not have to be provided for bomber production while the Air Force carried out its plan to purchase KC-46A tankers and F-35A fighters and to develop other aircraft, including helicopters, an aircraft for training new pilots, and a replacement for Air Force One. Another advantage of this option is that a bomber program that begins later might be able to take advantage of any general advances in aerospace technology that are made in the coming years. Such advances might make possible an even more capable bomber or might lead to other types of weapons that would make a new bomber unnecessary or reduce the number of bombers needed. Taking advantage of future technological developments could be particularly valuable for weapon systems that are expected to be in use for several decades. Even with a 10-year delay, a new bomber would still be available before today's bombers reached the end of their service life.

A disadvantage of this option is that if some current bombers need to be retired sooner than expected, a replacement would not be available. By 2035, the Air Force's B-52s will be about 75 years old, its B-1Bs will be about 50 years old, and its B-2As about 40 years old. Expecting those aircraft to perform reliably after that much time may prove to be overly optimistic. Similarly, a gap in capability could arise if the new bomber was deferred and ended up taking significantly more time to field than expected (as has been the case for the F-35 fighter program). Another disadvantage is that the Air Force's inventory of stealthy bombers that are able to fly in defended airspace would remain limited to the B-2A, which makes up only 13 percent of today's bomber force. Larger numbers of stealthy bombers might be useful in operations against adversaries that employed advanced air defenses. A third disadvantage is that fewer bombers would be available for operations in places like the western Pacific Ocean, where long distances and limited basing options would make long-range aircraft such as the B-21 particularly useful during a conflict.