Verbseoul.
하다 verb
보증하다bojeunghadato guarantee

To say to guarantee politely in the present tense, use 보증해요 (boh-cheung-hae-yoh). Below is the full conjugation of 보증하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
보증해
boh-cheung-hae
보증해요
boh-cheung-hae-yoh
보증합니다
boh-cheung-hahm-nee-dah
Past
보증했어
boh-cheung-hae-ssuh
보증했어요
boh-cheung-hae-ssuh-yoh
보증했습니다
boh-cheung-hae-sseum-nee-dah
Future
보증할 거야
boh-cheung-hahl- -guh-yah
보증할 거예요
boh-cheung-hahl- -guh-yae-yoh
보증할 겁니다
boh-cheung-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
보증하세요
boh-cheung-hah-sae-yoh
Suggestion / Let's Polite (요)
보증해요
boh-cheung-hae-yoh
Question Polite (요)
보증해요?
boh-cheung-hae-yoh-?
Connective “and” — (고)
보증하고
boh-cheung-hah-goh
Conditional “if” — (면)
보증하면
boh-cheung-hah-myuhn
Noun form — (기)
보증함
boh-cheung-hahm