Present — what is happening now, and what happens habitually
| yo | sirvoI serve | nosotros | servimoswe serve |
| tú | sirvesyou serve | vosotros | servísyou all serve |
| él/ella/Ud. | sirvehe/she serves | ellos/Uds. | sirventhey serve |
Present perfect — have —ed; a past still touching now. Spain: today, this week. Latin America: mostly the indefinido instead
| yo | he servidoI have served | nosotros | hemos servidowe have served |
| tú | has servidoyou have served | vosotros | habéis servidoyou all have served |
| él/ella/Ud. | ha servidohe/she has served | ellos/Uds. | han servidothey have served |
Present subjunctive — after que with wishes, doubt, emotion, ojalá
| yo | sirva(that) I serve | nosotros | sirvamos(that) we serve |
| tú | sirvas(that) you serve | vosotros | sirváis(that) you all serve |
| él/ella/Ud. | sirva(that) he/she serves | ellos/Uds. | sirvan(that) they serve |
Present perfect subjunctive — have —ed, under doubt or emotion: no creo que haya venido
| yo | haya servido(that) I have served | nosotros | hayamos servido(that) we have served |
| tú | hayas servido(that) you have served | vosotros | hayáis servido(that) you all have served |
| él/ella/Ud. | haya servido(that) he/she has served | ellos/Uds. | hayan servido(that) they have served |
Preterite — a finished past action — it started, it ended
| yo | servíI served | nosotros | servimoswe served |
| tú | servisteyou served | vosotros | servisteisyou all served |
| él/ella/Ud. | sirvióhe/she served | ellos/Uds. | sirvieronthey served |
Imperfect — used to / was —ing; background, habits, descriptions
| yo | servíaI used to serve | nosotros | servíamoswe used to serve |
| tú | servíasyou used to serve | vosotros | servíaisyou all used to serve |
| él/ella/Ud. | servíahe/she used to serve | ellos/Uds. | servíanthey used to serve |
Past perfect — had —ed; further back than another past event
| yo | había servidoI had served | nosotros | habíamos servidowe had served |
| tú | habías servidoyou had served | vosotros | habíais servidoyou all had served |
| él/ella/Ud. | había servidohe/she had served | ellos/Uds. | habían servidothey had served |
Imperfect subjunctive — si clauses and past-tense wishes: si tuviera, quería que fuera
| yo | sirviera(that) I served | nosotros | sirviéramos(that) we served |
| tú | sirvieras(that) you served | vosotros | sirvierais(that) you all served |
| él/ella/Ud. | sirviera(that) he/she served | ellos/Uds. | sirvieran(that) they served |
Imperfect subjunctive — the same tense, second form; commoner in Spain and in writing
| yo | sirviese(that) I served | nosotros | sirviésemos(that) we served |
| tú | sirvieses(that) you served | vosotros | sirvieseis(that) you all served |
| él/ella/Ud. | sirviese(that) he/she served | ellos/Uds. | sirviesen(that) they served |
Past perfect subjunctive — had —ed, hypothetically: si hubiera sabido
| yo | hubiera servido(that) I had served | nosotros | hubiéramos servido(that) we had served |
| tú | hubieras servido(that) you had served | vosotros | hubierais servido(that) you all had served |
| él/ella/Ud. | hubiera servido(that) he/she had served | ellos/Uds. | hubieran servido(that) they had served |
Preterite perfect — had —ed, immediately before; literary, all but extinct
| yo | hube servidoI had served | nosotros | hubimos servidowe had served |
| tú | hubiste servidoyou had served | vosotros | hubisteis servidoyou all had served |
| él/ella/Ud. | hubo servidohe/she had served | ellos/Uds. | hubieron servidothey had served |
Future — will — (spoken Spanish often prefers voy a + infinitivo)
| yo | serviréI will serve | nosotros | serviremoswe will serve |
| tú | servirásyou will serve | vosotros | serviréisyou all will serve |
| él/ella/Ud. | serviráhe/she will serve | ellos/Uds. | serviránthey will serve |
Conditional — would —; also softens a request into politeness
| yo | serviríaI would serve | nosotros | serviríamoswe would serve |
| tú | serviríasyou would serve | vosotros | serviríaisyou all would serve |
| él/ella/Ud. | serviríahe/she would serve | ellos/Uds. | serviríanthey would serve |
Future perfect — will have —ed; done by some future point
| yo | habré servidoI will have served | nosotros | habremos servidowe will have served |
| tú | habrás servidoyou will have served | vosotros | habréis servidoyou all will have served |
| él/ella/Ud. | habrá servidohe/she will have served | ellos/Uds. | habrán servidothey will have served |
Conditional perfect — would have —ed; the road not taken
| yo | habría servidoI would have served | nosotros | habríamos servidowe would have served |
| tú | habrías servidoyou would have served | vosotros | habríais servidoyou all would have served |
| él/ella/Ud. | habría servidohe/she would have served | ellos/Uds. | habrían servidothey would have served |
Future subjunctive — legal and proverbial only: adonde fueres, haz lo que vieres
| yo | sirviere(should) I serve | nosotros | sirviéremos(should) we serve |
| tú | sirvieres(should) you serve | vosotros | sirviereis(should) you all serve |
| él/ella/Ud. | sirviere(should) he/she serve | ellos/Uds. | sirvieren(should) they serve |
Imperative (do it) — orders and requests; there is no yo form
| yo | — | nosotros | sirvamoslet's serve |
| tú | sirveserve! | vosotros | servidserve! |
| él/ella/Ud. | sirvaserve! | ellos/Uds. | sirvanserve! |
Imperative (don't) — no + subjunctive — never the affirmative form with no in front
| yo | — | nosotros | no sirvamoslet's not serve |
| tú | no sirvasdon't serve | vosotros | no sirváisdon't serve |
| él/ella/Ud. | no sirvadon't serve | ellos/Uds. | no sirvandon't serve |

Red = the form breaks the regular pattern. Everything in black you could have worked out from the endings alone.
I — the speaker
| Presente | sirvoI serve |
| Perfecto | he servidoI have served |
| Subj. presente | sirva(that) I serve |
| Subj. perfecto | haya servido(that) I have served |
| Futuro | serviréI will serve |
| Condicional | serviríaI would serve |
| Fut. perfecto | habré servidoI will have served |
| Cond. perfecto | habría servidoI would have served |
| Subj. futuro | sirviere(should) I serve |
| Indefinido | servíI served |
| Imperfecto | servíaI used to serve |
| Pluscuamp. | había servidoI had served |
| Subj. imperf. | sirviera(that) I served |
| Subj. -se | sirviese(that) I served |
| Subj. pluscuamp. | hubiera servido(that) I had served |
| Pret. anterior | hube servidoI had served |
| Imperativo | — |
| Imper. negativo | — |
we — the speaker plus others
| Presente | servimoswe serve |
| Perfecto | hemos servidowe have served |
| Subj. presente | sirvamos(that) we serve |
| Subj. perfecto | hayamos servido(that) we have served |
| Futuro | serviremoswe will serve |
| Condicional | serviríamoswe would serve |
| Fut. perfecto | habremos servidowe will have served |
| Cond. perfecto | habríamos servidowe would have served |
| Subj. futuro | sirviéremos(should) we serve |
| Indefinido | servimoswe served |
| Imperfecto | servíamoswe used to serve |
| Pluscuamp. | habíamos servidowe had served |
| Subj. imperf. | sirviéramos(that) we served |
| Subj. -se | sirviésemos(that) we served |
| Subj. pluscuamp. | hubiéramos servido(that) we had served |
| Pret. anterior | hubimos servidowe had served |
| Imperativo | sirvamoslet's serve |
| Imper. negativo | no sirvamoslet's not serve |
you (informal) — one person you are familiar with
| Presente | sirvesyou serve |
| Perfecto | has servidoyou have served |
| Subj. presente | sirvas(that) you serve |
| Subj. perfecto | hayas servido(that) you have served |
| Futuro | servirásyou will serve |
| Condicional | serviríasyou would serve |
| Fut. perfecto | habrás servidoyou will have served |
| Cond. perfecto | habrías servidoyou would have served |
| Subj. futuro | sirvieres(should) you serve |
| Indefinido | servisteyou served |
| Imperfecto | servíasyou used to serve |
| Pluscuamp. | habías servidoyou had served |
| Subj. imperf. | sirvieras(that) you served |
| Subj. -se | sirvieses(that) you served |
| Subj. pluscuamp. | hubieras servido(that) you had served |
| Pret. anterior | hubiste servidoyou had served |
| Imperativo | sirveserve! |
| Imper. negativo | no sirvasdon't serve |
you all — informal plural, Spain only
| Presente | servísyou all serve |
| Perfecto | habéis servidoyou all have served |
| Subj. presente | sirváis(that) you all serve |
| Subj. perfecto | hayáis servido(that) you all have served |
| Futuro | serviréisyou all will serve |
| Condicional | serviríaisyou all would serve |
| Fut. perfecto | habréis servidoyou all will have served |
| Cond. perfecto | habríais servidoyou all would have served |
| Subj. futuro | sirviereis(should) you all serve |
| Indefinido | servisteisyou all served |
| Imperfecto | servíaisyou all used to serve |
| Pluscuamp. | habíais servidoyou all had served |
| Subj. imperf. | sirvierais(that) you all served |
| Subj. -se | sirvieseis(that) you all served |
| Subj. pluscuamp. | hubierais servido(that) you all had served |
| Pret. anterior | hubisteis servidoyou all had served |
| Imperativo | servidserve! |
| Imper. negativo | no sirváisdon't serve |
he, she, you (formal) — one other person — formal you shares it
| Presente | sirvehe/she serves |
| Perfecto | ha servidohe/she has served |
| Subj. presente | sirva(that) he/she serves |
| Subj. perfecto | haya servido(that) he/she has served |
| Futuro | serviráhe/she will serve |
| Condicional | serviríahe/she would serve |
| Fut. perfecto | habrá servidohe/she will have served |
| Cond. perfecto | habría servidohe/she would have served |
| Subj. futuro | sirviere(should) he/she serve |
| Indefinido | sirvióhe/she served |
| Imperfecto | servíahe/she used to serve |
| Pluscuamp. | había servidohe/she had served |
| Subj. imperf. | sirviera(that) he/she served |
| Subj. -se | sirviese(that) he/she served |
| Subj. pluscuamp. | hubiera servido(that) he/she had served |
| Pret. anterior | hubo servidohe/she had served |
| Imperativo | sirvaserve! |
| Imper. negativo | no sirvadon't serve |
they, you all — several others — plural you shares it
| Presente | sirventhey serve |
| Perfecto | han servidothey have served |
| Subj. presente | sirvan(that) they serve |
| Subj. perfecto | hayan servido(that) they have served |
| Futuro | serviránthey will serve |
| Condicional | serviríanthey would serve |
| Fut. perfecto | habrán servidothey will have served |
| Cond. perfecto | habrían servidothey would have served |
| Subj. futuro | sirvieren(should) they serve |
| Indefinido | sirvieronthey served |
| Imperfecto | servíanthey used to serve |
| Pluscuamp. | habían servidothey had served |
| Subj. imperf. | sirvieran(that) they served |
| Subj. -se | sirviesen(that) they served |
| Subj. pluscuamp. | hubieran servido(that) they had served |
| Pret. anterior | hubieron servidothey had served |
| Imperativo | sirvanserve! |
| Imper. negativo | no sirvandon't serve |

Red = the form breaks the regular pattern. Everything in black you could have worked out from the endings alone.