For a study of spending by Senators, see David C.W. Parker and Craig Goodman, "Our State's Never Had Better Friends: Resource Allocation, Home Styles, and Dual Representation in the Senate," Political Research Quarterly, vol. 66, no. 2 (June 2013), pp. 370-384. For a study of House Member spending, see David C.W. Parker and Craig Goodman, "Making a Good Impression: Resource Allocation, Home Styles, and Washington Work," Legislative Studies Quarterly, vol. 34, no. 4 (November 2009), pp. 493-524.

P.L. 100-137, Oct. 21, 1987, 101 Stat. 814, 2 U.S.C. §6313.

Available at http://www.rules.senate.gov/public/index.cfm?p=RulesOfSenateHome. In particular, Rule XXXVIII (Prohibition on Unofficial Office Accounts); Rule XLII (Employment Practices); and Rule XLIII (Representation by Members).

Guidelines from the Senate Committee on Rules and Administration may be found in the Senate Handbook, "Amendments to Regulations Adopted by the Committee on Rules and Administration," and other committee communications. For example, see Senator Schumer, "Amendments to Regulations Adopted by the Committee on Rules and Administration," Congressional Record, daily edition, June 12, 2012, p. S3970, which contains information on Senate Office Building regulations, including the smoking policy, building hours, and building admission.

Guidelines from the Senate Ethics Committee may be found in the Senate Ethics Manual, "Dear Colleague" letters, and other committee communications.

For example, the period of availability of funds is addressed in statute and discussed in GAO's Principles of Federal Appropriations Law, which states, "Pursuant to law, late-arriving bills may be paid for up to two years following the end of the fiscal year" (Chapter 5, Availability of Appropriations: Time, Page 5-76: http://www.gao.gov/special.pubs/3rdEditionVol1.pdf). See also 2 U.S.C. §4575, which addresses the "Gross rate of compensation of employees paid by Secretary of Senate," and 2 U.S.C. §4571, which addresses "Senate pay adjustments; action by President pro tempore of Senate." The latter authorizes the Order of the President pro Tempore, which establishes maximum and minimum rates of pay for employees within various categories of Senate offices.

2 U.S.C. §4108. P.L. 103-283, the FY1995 Legislative Branch Appropriations Act, amended this section to require summaries of each office's account, stating the total amount of appropriations made available or allocated to the office; any supplemental appropriation, transfer of funds, or rescission; total expenses incurred for salary and office expenses; and the unexpended balance. During consideration of the FY2010 legislative branch appropriations bill (H.R. 2918), the Senate agreed to an amendment, S.Amdt. 1369, offered by Senator Coburn, adding a provision to this section requiring the online publication of the reports in a "searchable, itemized format." The provision was subsequently included in the law enacted on October 1, 2009 (P.L. 111-68). Reports since the period covering April 1, 2011-September 30, 2011, are available at http://www.senate.gov/legislative/common/generic/report_secsen.htm.

Data exclude Senators who were not in office for the entirety of the fiscal year.

These include funds operated by the Sergeant at Arms, including the Economic Allocation Fund (for information technology and other equipment), the Numeric Allocation Program (for telecom equipment) and the Constituent Service System Fund (hardware and software to support approved systems). Rental charges for home state offices are paid for by the Senate Sergeant at Arms. For information on authorization for procurement and payment of certain services, including home state office space and furniture, see 2 U.S.C. §6313 et seq.

For example, "An Act for allowing full mileage to the members of the Senate and House of Representatives of the United States" was enacted on July 6, 1797 (1 Stat. 533, ch. 13).

Senators who were not chairmen of committees were first provided clerical assistance, at a rate of $6 a day when the Senate was in session, in 1884 (23 Stat. 249). Committees had previously been provided staffing assistance (an "act making appropriations for the legislative, executive, and judicial expenses of government for the year ending June 30, 1857" provided funding for "clerks to committees" and the Senate Finance Committee in particular [11 Stat. 103]).

June 14, 1948, ch. 467, 62 Stat. 425. See also former 2 U.S.C. §52 (repealed) for a list of additional laws.

P.L. 100-137, October 21, 1987, 101 Stat. 814, 2 U.S.C. §6313.

Prior to the 1987 legislation, funding for these items was contained within separate line-items for "administrative, clerical and legislative assistance to Senators" and "agency contributions," (both within the heading "salaries, officers and employees") and "official office expense allowances" (in the Senate appropriation account "Miscellaneous Items," under the heading "Contingent Expenses of the Senate"). The "administrative, clerical and legislative assistance to Senators" line-item was itself a consolidation, effective October 1, 1977, of two previously separate allowances, the Administrative and Clerical Assistance Allowance and the Legislative Assistance Allowance. See U.S. Congress, Senate, Committee on Appropriations, Legislative Branch Appropriations, 1978, report to accompany H.R. 7932. S.Rept. 95-338, 95^th Cong., 1^st Sess. (Washington, GPO: 1977); and P.L. 95-94, 91 Stat. 662-663, August 5, 1977. The Senate, in the early 1980s, also provided for limited transfer authority between the accounts (see former Section 2 U.S.C. §58b).

U.S. Congress, Senate Committee on Rules and Administration, Combining the Senators' Clerk Hire Allowance and the Senators' Official Office Expense Account into a Combined Single Account to be Known as the 'Senators' Official Personnel and Office Expense Account,' report to accompany S. 1574, 100^th Cong., 1^st sess., July 30, 1987, S.Rept. 100-134 (Washington: GPO, 1987).

For legislation introduced in the Senate mentioning the SOPOEA, see, for example, the following: in the 115^th Congress, S. 2917, S. 2236, and S. 2872; in the 114^th Congress, S. 3327; in the 112^th Congress, S. 81; in the 111^th Congress, S. 1808 and S. 3335 (S.Rept. 111-365); in the 110^th Congress, S. 1 (which became P.L. 110-81); in the 108^th Congress, S. 3741; and in the 103^rd Congress, S. 1287. Other bills have been introduced in the House that would affect both House and Senate allowances, for example: in the 116^th Congress, H.R. 577 and H.R. 1626; in the 115^th Congress, H.R. 839, H.R. 2951, and H.R. 6640; in the 114^th Congress, H.R. 1873 and H.R. 5741; and in the 113^th Congress, H.R. 4872 and H.Con.Res. 113. For additional information on recent provisions in appropriations acts, see "Appropriations Acts: Administrative Provisions and Report Language Related to Unexpended Balances."

The committee reports generally state: "It should also be noted that the figures in the following table are preliminary, and that official notification of member budgets is issued by the Financial Clerk of the Senate after enactment of this bill." For example, see U.S. Congress, Senate Committee on Appropriations, Legislative Branch Appropriations, 2020, report to accompany S. 2581, S.Rept. 116-124, 116^th Cong., 1^st sess., (Washington: GPO, 2019), p. 24.

Agency contributions include any government contributions as an employer toward health and life insurance, retirement, and FICA. These contributions are funded in the SOPOEA account but separate from each Senator's individual authorization.

For example, see U.S. Congress, Senate Committee on Appropriations, Legislative Branch Appropriations, 2020, report to accompany S. 2581, S.Rept. 116-124, 116^th Cong., 1^st sess., (Washington: GPO, 2019), p. 24.

For example, see the FY2010 Legislative Branch Appropriations Act (P.L. 111-68, Oct. 1, 2009, 123 Stat. 2026) and the FY2009 Omnibus Appropriations Act (P.L. 111-8, March 11, 2009, 123 Stat. 814). Additional adjustments authorized in the Order of the President pro Tempore. For additional adjustment information, including a history of adjustments in the appropriations acts and in the Orders, see notes accompanying 2 U.S.C. §4575. See also a general provision in P.L. 116-94 adjusting the maximum rates of compensation for certain congressional staff.

P.L. 76-641, June 18, 1940, 54 Stat. 464.

P.L. 90-57, July 28, 1967, 81 Stat. 141-144; 2 U.S.C. §4575. The Senate Appropriations Committee report from that year discusses the changes and contains a table for the allowances for the various population categories as well as has an "anticipated ... saving of approximately 3 percent, based upon a historic nonuse of all basic allowances by all Senators." (U.S. Congress, Senate Appropriations Committee, Legislative Branch Appropriations, 1968, report to accompany H.R. 10368, 90^th Cong., 1^st sess., June 29, 1967, S.Rept. 90-393 (Washington: GPO, 1967), pp. 5-8).

2 U.S.C. §4575.

Ibid., pp. 24-25. The Senate Appropriations Committee has not issued a FY2021 legislative branch appropriations report, and the legislative branch is operating on a continuing appropriations resolution through December 11, 2020 (P.L. 116-159).

S.Res. 60 (94^th Cong); P.L. 94-59 (July 25, 1975, 89 Stat. 274-5, 276-8); P.L. 95-26 (May 4, 1977, 91 Stat. 83); and P.L. 95-94, Aug. 5, 1977, 91 Stat. 662.

The debates on the establishment of the legislative assistance allowance provide a lengthy discussion of the appropriate means of providing Senators with support for their committee responsibilities as well as challenges. U.S. Congress, Senate Committee on Rules and Administration, Hearings on S.Res. 60 and S.Res. 110, Authorizing Each Member of the Senate to Employ Additional Assistants to Work on Matters Pertaining to Committees on Which Senators Serve, 94^th Cong., 1^st sess., April 30, 1975 and May 20, 1975 (Washington: GPO, 1975); U.S. Congress, Senate Committee on Rules and Administration, Additional Senate Committee Employees, report to accompany S.Res. 60, 94^th Cong., 1^st sess., June 5, 1975, S.Rept. 94-185 (Washington: GPO, 1975); "Additional Senate Committee Employees," Remarks in the Senate, Congressional Record, vol. 121, June 11, 1975, pp.18299-18408.

Originally proposed to assist Senators without access to significant committee staffing and resources, the legislative assistance allowance was reduced for any chair or ranking member of a full committee or subcommittee with control over funding for staffing in its earliest years. The distinction between committee leaders and other Senators, however, was suspended (S.Res. 85, §23 [99^th Cong.] and S.Res. 34 [100^th Cong.]) and then repealed with the enactment of the SOPOEA. This allowance is one of the three components of the SOPOEA, although the Senate Appropriations Committee reports accompanying the annual appropriations bills state, "that the amounts provided for the various components of the SOPOEA are interchangeable" (U.S. Congress, Senate Committee on Appropriations, Legislative Branch Appropriations, 2020, report to accompany S. 2581, S.Rept. 116-124, 116^th Cong., 1^st sess., (Washington: GPO, 2019), pp. 24-25).

Ibid.

For example, mass mailings may not exceed $50,000 per fiscal year, and additional official mail regulations may be established in statute, regulations and rules of the Senate, the Senate Committee on Rules and Administration, and the Senate Ethics Committee (FY1995 Legislative Branch Appropriations Act, P.L. 103-283, July 22, 1994, 108 Stat. 1427, 39 U.S.C. §3210).

P.L. 97-51, 95 Stat. 966, September 11, 1981.

U.S. Congress, Senate Committee on Appropriations, Legislative Branch Appropriations, 2020, report to accompany S. 2581, S.Rept. 116-124, 116^th Cong., 1^st sess., (Washington: GPO, 2019), pp. 24-25.

P.L. 114-113, December 18, 2016. A similar administrative provision was previously included in the Senate Appropriations Committee's reported version of the bill (H.R. 2250). Chapter 5, "Availability of Appropriations: Time" of the Government Accountability Office's Principles Of Federal Appropriations Law provides some background information on Treasury operations and the treatment of closed appropriations: "We commonly talk about 'returning' appropriation balances to the Treasury. In point of fact, for the most part, they never leave the Treasury to begin with. An appropriation does not represent cash actually set aside in the Treasury. Government obligations are liquidated as needed through revenues and borrowing. Thus, the reversion of funds to the Treasury is not a movement of actual cash, but a bookkeeping adjustment that in the various ways discussed in the text, affects the government's legal authority to incur obligations and make expenditures." United States General Accounting Office, Principles of Federal Appropriations Law, Third Edition, vol. I, January 2004, http://www.gao.gov/special.pubs/3rdEditionVol1.pdf, pp. 5-73. A similar administrative provision related to the Members' Representational Allowance (MRA)—which supports office operations for Members of the House—has been included in the House of Representatives section of the appropriations acts for many years. For additional information, see "Appropriations Acts: Administrative Provisions Related to Unexpended Balances" in CRS Report R40962, Members' Representational Allowance: History and Usage, by Ida A. Brudnick.

P.L. 111-68, 2 U.S.C. §4108. Reports since the period covering April 1, 2011-September 30, 2011, are available at http://www.senate.gov/legislative/common/generic/report_secsen.htm. Each report contains information on the prior two fiscal years, so the initial report allows for the capturing of FY2009 and FY2010 data.

The two-year period for late receipts for Congress is shorter relative to annual appropriations for much of the rest of the federal government, which is subject to a five-year period (31 U.S.C. §1551 et al.). This is discussed in the Government Accountability Office's Principles of Federal Appropriations Law. This publication states: "For appropriations of the House and Senate, unobligated balances more than two years old cannot be used short of an act of Congress. Instead, obligations chargeable to appropriations that have been expired for more than 2 years 'shall be liquidated from any appropriations for the same general purpose, which, at the time of payment, are available for disbursement.' 2 U.S.C. §102a." United States General Accounting Office, Principles of Federal Appropriations Law, Third Edition, vol. I, January 2004, http://www.gao.gov/special.pubs/3rdEditionVol1.pdf, pp. 5-76-5-77.

See U.S. Office of Management and Budget, OMB Circular A-11, 2020 edition, https://www.whitehouse.gov/omb/information-for-agencies/circulars/.