Page 462 - Basic Japanese

polite speech it is inflected only for the imperfect -masu, the

perfect -mashita, and the tentative -mashō. But in honorific
speech, -masu is inflected for all categories except the

infinitive. These polite forms are used at the end of

sentence fragments, and also in the middle of sentences
instead of the usual plain forms, to make the entire
expression a bit more honorific:

Soko e irasshaimashite… You go there and…

Soko e irasshaimashitara… If you go there …

Please go there.
Soko e

irasshite

kudasaimase.

Here are the inflections of the polite verb -masu:

Imperfect: -masu
Tentative: -mashō

Infinitive: --
Provisional: -maseba

Imperative: -mase

Perfect: -mashita