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Mexico's political system and how laws are made: what investors need to know

Last verified: 2026-10-26 · Status: Changing

Mexico is a federal republic of 31 states and Mexico City. The President serves one six year term with no reelection ever, and the current term runs to 30 September 2030; Congress has 500 deputies elected every three years and 128 senators elected every six, and the next federal midterm vote is on 6 June 2027. Bills on taxes and loans must start in the Chamber of Deputies, the President has 30 days to object to a bill, and a veto falls only with two thirds of the votes in each chamber. Constitutional amendments need two thirds of Congress members present plus a majority of state legislatures, and since October 2024 they cannot be challenged before the Supreme Court. The 2024 judicial reform made judges elected by popular vote; a June 2026 amendment moved the remaining judicial seats to an election on 4 June 2028.

Key facts

Presidential term, single term with no reelection ever	6 yearsConstitution art. 83, as of 2026-10-07 · in force
End of the current presidential term	2030-09-30 dateConstitution art. 83, as of 2024-10-01 · in force
Next ordinary federal election (Chamber of Deputies, first Sunday of June)	2027-06-06 dateLGIPE art. 22(1); Constitution art. 51, as of 2026-06-02 · in force
Seats in the Chamber of Deputies (300 plurality, 200 proportional)	500 seatsConstitution art. 52, as of 2019-06-06 · in force
Term of federal deputies	3 yearsConstitution art. 51, as of 1977-12-06 · in force
Seats in the Senate	128 seatsConstitution art. 56, as of 1996-08-22 · in force
Term of senators	6 yearsConstitution art. 56, as of 1996-08-22 · in force
Federal entities (31 states plus Mexico City)	32 entitiesConstitution art. 43, as of 2016-01-29 · in force
Vote needed to amend the Constitution	Two thirds of members present in Congress plus a majority of the 32 local legislatures ruleConstitution art. 135, as of 2016-01-29 · in force
Vote needed to override a presidential veto	Two thirds of total votes in each chamber ruleConstitution art. 72 C, as of 1917-02-05 · in force
Days the Executive has to return a bill with objections before it is deemed approved	30 calendar daysConstitution art. 72 B, as of 2011-08-17 · in force
Days each chamber has to vote a presidential preferential bill	30 calendar daysConstitution art. 71, as of 2012-08-09 · in force
Chamber where tax and loan bills must start	Chamber of Deputies ruleConstitution art. 72 H, as of 1917-02-05 · in force
Year from which consecutive reelection of federal legislators is banned	2030 yearConstitution art. 59; DOF 1 April 2025, transitory Third, as of 2025-04-01 · in force
Date of the next federal and local judicial election	2028-06-04 dateDOF 2 June 2026 judicial reform decree, transitory Third, as of 2026-06-02 · in force

The rule

1. A federal republic. Mexico is a representative, democratic, secular and federal republic made up of free and sovereign states and Mexico City. The federation has 31 named states plus Mexico City, and any power not expressly granted to federal officials by the Constitution is reserved to the states or Mexico City. For an investor this means state laws govern matters such as property registries, state payroll taxes and local permits, while tax, trade, labor, banking and foreign investment rules are federal.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026), Art. 40, art. 43 and art. 124, 1917-02-05 official text · verified 2026-10-26

2. The President serves one six year term and can never return. The President takes office on 1 October and serves six years; anyone who has held the office, whether elected, interim, substitute or provisional, may never hold it again. The current term began on 1 October 2024 and ends on 30 September 2030. A reform published on 7 October 2026 requires future Presidents (and state governors and the head of government of Mexico City) to be Mexican by birth with no other nationality, and bars them from using a foreign passport while in office; it applies from the 2028 electoral process and not to current office holders.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026); Decreto en materia de nacionalidad única, DOF 7 October 2026, Art. 82 and art. 83; decree transitory articles Second and Third, 2026-10-07 official text · verified 2026-10-26 · changed: Decree published in the DOF on 7 October 2026 amended arts. 82, 116 and 122 to require single Mexican nationality for the President, governors and the head of government of Mexico City, applicable from the 2028 electoral process.

3. A two chamber Congress with staggered terms. The Chamber of Deputies has 500 members, 300 elected by plurality in single member districts and 200 by proportional representation from regional lists, and is renewed in full every three years. The Senate has 128 members: in each state and in Mexico City two are elected by plurality and one goes to the first minority, and 32 are elected by proportional representation from a single national list; it is renewed in full every six years. Ordinary federal elections are held on the first Sunday of June, so the next vote for deputies is on 6 June 2027.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026); Ley General de Instituciones y Procedimientos Electorales (DOF 23 May 2014, last reform DOF 2 June 2026), Constitution art. 50, art. 51, art. 52 and art. 56; LGIPE art. 22(1), 2014-05-23 official text · verified 2026-10-26

4. Consecutive reelection of legislators ends from 2030. A decree published on 1 April 2025 reinstated the ban on consecutive reelection of senators and deputies (and of mayors and local legislators), together with a ban on close relatives of the outgoing office holder running to succeed them. Both bans apply from the 2030 federal and local elections, and anyone holding those offices in 2030 cannot run for reelection.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026); Decreto en materia de no reelección y nepotismo electoral, DOF 1 April 2025, Art. 59; decree transitory articles Second and Third, 2025-04-01 official text · verified 2026-10-26 · changed: From the 2030 elections, senators and deputies can no longer be reelected for the immediately following term (DOF 1 April 2025). Before this reform, consecutive reelection had been allowed since the 2014 political reform.

5. When Congress sits. Congress meets in a first ordinary period from 1 September, which may run to 15 December (to 31 December in the year a new President takes office), and a second period from 1 February to no later than 30 April. In recesses a Permanent Commission of 37 members (19 deputies and 18 senators) sits; it can approve some appointments and receive vetoed bills, but does not pass laws.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026), Art. 65, art. 66 and art. 78, 1917-02-05 official text · verified 2026-10-26

6. Who can propose laws, and the President's fast track. Bills may be introduced by the President, by federal deputies and senators, by state legislatures and Mexico City's legislature, and by citizens equal to at least 0.13 percent of the electoral roll. On the opening day of each ordinary period the President may file up to two preferential bills (or flag two pending ones); each chamber must then vote within 30 calendar days or the bill becomes the first item at the next plenary session. Constitutional amendments cannot use this fast track.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026), Art. 71, 2012-08-09 official text · verified 2026-10-26

7. How a bill becomes law. Every bill not reserved to one chamber is debated in both. Bills on loans, contributions or taxes, and on recruiting troops, must be debated first in the Chamber of Deputies. Once both chambers approve, the Executive has 30 calendar days to return it with objections; if it does not, the bill is deemed approved and must be promulgated and published within 10 more days, failing which the president of the chamber of origin orders publication in the Diario Oficial de la Federación (DOF). A bill objected to by the Executive becomes law if both chambers confirm it by two thirds of the total votes. Laws bind only once published in the DOF.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026), Art. 72, sections A, B, C and H, 2011-08-17 official text · verified 2026-10-26

8. Amending the Constitution, and no court challenge to amendments. An amendment needs the vote of two thirds of the members present in Congress and approval by a majority of the state legislatures and Mexico City's legislature (17 of 32). Since a decree published on 31 October 2024, constitutional controversies and actions of unconstitutionality against amendments to the Constitution are inadmissible, so an amendment that changes the rules for a sector cannot be struck down by the Supreme Court on those routes.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026); Decreto en materia de inimpugnabilidad de las adiciones o reformas a la Constitución Federal, DOF 31 October 2024, Art. 135; art. 105, fifth paragraph (added DOF 31 October 2024), 2024-10-31 official text · verified 2026-10-26 · changed: A paragraph added to art. 105 on 31 October 2024 made constitutional controversies and actions of unconstitutionality inadmissible against constitutional amendments.

9. Treaties rank with federal law under the Constitution. The Senate approves the international treaties the Executive signs, and also decisions to terminate, denounce, suspend or amend them. The Constitution, federal laws that derive from it and treaties that conform to it are the supreme law of the Union, and state judges must follow them over contrary state law. Trade agreements such as the USMCA and tax treaties therefore apply nationwide once approved by the Senate and published.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026), Art. 76, section I; art. 133, 2007-02-12 official text · verified 2026-10-26

10. Elected judges and the 2028 judicial election. Supreme Court justices, electoral magistrates, members of the Judicial Discipline Tribunal, circuit magistrates and district judges are elected by popular vote. A constitutional reform published on 2 June 2026 moved every judicial seat not renewed in the 2025 election, plus vacancies, to a federal and local judicial election on the first Sunday of June 2028 (4 June 2028); judges whose terms would have ended in 2027 stay until then, the people elected take office before the Senate on 1 September 2028, and circuit magistrates and district judges elected in 2028 serve eight years, to 2036. The same reform moved any presidential recall vote to the first Sunday of June of the fourth year of the term, on the same day as ordinary elections.Constitución Política de los Estados Unidos Mexicanos (DOF 5 February 1917, consolidated text to DOF 7 October 2026); Decreto en materia de reforma al Poder Judicial, DOF 2 June 2026, Art. 35, section IX, item 3o; art. 96; decree transitory articles Second, Third and Seventh, 2026-06-02 official text · verified 2026-10-26 · changed: Decree published in the DOF on 2 June 2026 postponed the second judicial election from 2027 to 4 June 2028 and aligned the presidential recall vote with ordinary election days. See also disputes/judicial-reform.

Date	Event	Rule
By 31 October each year	Senate deadline to approve the Federal Revenue Law for the next year	LFPRH art. 42 IV
By 15 November each year	Chamber of Deputies deadline to approve the federal budget	Constitution art. 74 IV
15 December	Latest close of Congress's first ordinary period	Constitution art. 66
1 February to 30 April	Second ordinary period of Congress	Constitution art. 65 and art. 66
6 June 2027	Federal midterm election: all 500 deputies	Constitution art. 51; LGIPE art. 22
4 June 2028	Federal and local judicial election, and the date that falls in the window for any presidential recall vote	DOF 2 June 2026 decree; Constitution art. 35 IX
1 September 2028	People elected judges take office before the Senate	DOF 2 June 2026 decree, transitory Third
2030	Presidential and congressional elections; first elections under the reelection and nepotism bans	Constitution art. 59 and art. 83; DOF 1 April 2025
30 September 2030	End of the current presidential term	Constitution art. 83

Political and legislative calendar that matters for investors, from the Constitution and electoral law as verified on 26 October 2026.

Worked example

A tax bill filed by the President in September follows this path: it must start in the Chamber of Deputies (art. 72 H), then goes to the Senate. If both pass it on, say, 20 and 30 October, the Executive has until 29 November to object (30 calendar days); without objections it must be published in the DOF and only then binds taxpayers.
If the Executive objects, the bill returns to the Chamber of Deputies and becomes law only if two thirds of the total votes in each chamber confirm it (art. 72 C).
A sector reform done by constitutional amendment needs two thirds of the members present in each chamber plus 17 of the 32 local legislatures; once declared approved, it cannot be challenged through a constitutional controversy or an action of unconstitutionality (art. 105, fifth paragraph).

Step by step

1. Read the Diario Oficial de la Federación (DOF): a law, decree or regulation binds only from publication, and the transitory articles at the end set when each change takes effect.
2. For pending bills, track the chamber of origin and the committee: initiatives are discussed first in the chamber where they are filed (art. 72 I), and tax and loan bills always start in the Chamber of Deputies.
3. Watch 1 September and 1 February, when the President may file up to two preferential bills that each chamber must vote within 30 days.
4. Mark the electoral calendar: 6 June 2027 (deputies), 4 June 2028 (judges) and 2030 (President and Congress). Contract disputes that will reach federal courts after 2028 may be heard by newly elected judges.
5. For state level issues (property registry, payroll tax, local permits), read the state constitution and laws; residual powers belong to the states (art. 124).

Common traps

Treating a reform approved by Congress as law. It binds only after publication in the DOF and from the dates in its transitory articles; many 2025 and 2026 constitutional reforms gave Congress 90 or 180 days to amend secondary laws.
Assuming a constitutional amendment can be fought in the Supreme Court. Since 31 October 2024, constitutional controversies and actions of unconstitutionality against amendments are inadmissible.
Reading 'no reelection' as already in force for legislators. The renewed ban on consecutive reelection of deputies and senators starts with the 2030 elections.
Planning around a 2027 judicial election. The June 2026 reform moved the remaining judicial seats to 4 June 2028.
Forgetting the transition year calendar. In the year a new President takes office the budget package is due by 15 November instead of 8 September (art. 74 IV), and the first congressional period may run to 31 December (art. 66).

Sources

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