Some Portuguese verbs change their spelling when conjugated, but these are not irregular verbs. The consonant at the end of the stem simply adjusts its spelling so the pronunciation stays the same. This happens because Portuguese spelling rules assign different sounds to certain letters depending on the vowel that follows them.
The principle
In Portuguese, the letters c, g, ç, and the digraph qu change their sound depending on the next vowel. For example, c before a/o/u sounds like /k/, but before e/i it sounds like /s/. When you conjugate a verb and the ending vowel changes, the consonant spelling must shift to preserve the original sound of the infinitive.
C → QU before e/i (-car verbs)
Verbs ending in -car have a /k/ sound in the stem. Before -ar, -a, -o, the letter c already represents /k/. But before e or i, a plain c would be read as /s/. The solution: write qu to keep the /k/ sound.
This affects the preterite 1st person singular (ending -ei) and the entire present subjunctive (endings with -e).
| Subject | Preterite of ficar | Note |
|---|---|---|
| eu | fiquei | c → qu (before e) |
| tu | ficaste | no change (before a) |
| ele / ela / você | ficou | no change (before o) |
| nós | ficámos | no change (before a) |
| eles / elas / vocês | ficaram | no change (before a) |
Only the eu form changes -- every other person keeps the regular c because the following vowel is a or o.
Toquei guitarra no concerto de sábado.
I played guitar at the Saturday concert.
Common -car verbs: ficar (to stay), tocar (to play/touch), explicar (to explain), brincar (to play), indicar (to indicate), comunicar (to communicate), aplicar (to apply).
G → GU before e/i (-gar verbs)
Verbs ending in -gar have a hard /g/ sound. Before e or i, a plain g would be read as /ʒ/ (like the s in English "measure"). The fix: write gu to preserve /g/.
The affected positions are exactly the same as for -car verbs: preterite 1st person singular and the present subjunctive.
Cheguei atrasado porque paguei a conta no café.
I arrived late because I paid the bill at the cafe.
Joguei futebol com os meus amigos ontem à tarde.
I played football with my friends yesterday afternoon.
Common -gar verbs: chegar (to arrive), jogar (to play a game), pagar (to pay), entregar (to deliver), apagar (to erase/turn off), investigar (to investigate), obrigar (to oblige).
Ç → C before e/i (-çar verbs)
Verbs ending in -çar have an /s/ sound in the stem. The cedilla (ç) is what gives c the /s/ sound before a/o/u. But before e or i, a plain c already sounds like /s/ -- so the cedilla is simply dropped.
Comecei a estudar português em janeiro.
I started studying Portuguese in January.
Dancei a noite toda na festa.
I danced all night at the party.
Almocei com a minha família no domingo.
I had lunch with my family on Sunday.
Common -çar verbs: começar (to begin), dançar (to dance), almoçar (to have lunch), abraçar (to hug), lançar (to launch), alcançar (to reach/achieve), avançar (to advance).
GU → G before o/a (-guir verbs)
Verbs ending in -guir use gu to represent the /g/ sound before -ir. In the 1st person present indicative (ending -o) and the present subjunctive (endings with -a), the g alone already sounds like /g/ before o or a, so the u is dropped.
Eu sigo sempre o mesmo caminho para o trabalho.
I always follow the same route to work.
Consigo ver a torre daqui.
I can see the tower from here.
Common -guir verbs: seguir (to follow), conseguir (to manage/achieve), distinguir (to distinguish), perseguir (to pursue), prosseguir (to proceed).
G → J before o/a (-ger and -gir verbs)
Verbs ending in -ger or -gir use g for the /ʒ/ sound before e or i. In the 1st person present indicative (ending -o) and the present subjunctive (endings with -a), the letter g would sound like hard /g/. The solution: write j, which always represents /ʒ/ regardless of the following vowel.
Eu protejo os meus filhos de tudo.
I protect my children from everything.
Dirijo uma pequena empresa em Coimbra.
I manage a small company in Coimbra.
Common -ger/-gir verbs: proteger (to protect), eleger (to elect), dirigir (to drive/direct), fingir (to pretend), exigir (to demand), corrigir (to correct).
Summary of all patterns
| Verb ending | Change | When | Example |
|---|---|---|---|
| -car | c → qu | before e/i | ficar → fiquei |
| -gar | g → gu | before e/i | chegar → cheguei |
| -çar | ç → c | before e/i | começar → comecei |
| -guir | gu → g | before o/a | seguir → sigo |
| -ger / -gir | g → j | before o/a | proteger → protejo |
Where these changes appear
Not every tense triggers a spelling change. The change only happens when the ending starts with a vowel different from the one in the infinitive. Here is a quick reference:
| Tense / Form | -car, -gar, -çar | -guir, -ger, -gir |
|---|---|---|
| Present indicative (eu) | no change | change (sigo, protejo) |
| Preterite (eu) | change (fiquei, cheguei, comecei) | no change |
| Present subjunctive (all forms) | change (fique, fiques...) | change (siga, proteja...) |
| All other tenses | no change | no change |
The key insight
These spelling changes are not irregularities to memorize -- they are the natural result of how Portuguese spelling works. The sound of the verb never changes; only the letters on the page adjust. When you see fiquei instead of ficei, it is not a new form to learn but the same /k/ sound written the only way Portuguese allows before an e.
Think of the infinitive's sound as the anchor. If ficar has a /k/, every conjugated form must have that same /k/. The spelling simply follows.
For verbs with actual changes to the stem vowel, see Stem-Changing Verbs. For the full preterite tense, see Preterite Overview.
Related Topics
- Conjugation BasicsA1 — How Portuguese verbs change form to express person, number, tense, and mood
- The Three Conjugation Classes (-ar, -er, -ir)A1 — Overview of the three verb classes and their base endings
- Stem-Changing Verbs OverviewA2 — Verbs whose stems change in certain forms
- Pretérito Perfeito Simples OverviewA2 — The simple past tense for completed actions
- Present Subjunctive OverviewB1 — How the presente do conjuntivo is formed, why it exists, and the five big families of situations that trigger it.