"저는 곧 침대보를 세탁합니다."
Translation:I am going to wash the bed sheet soon.
"I soon wash a duvet" sounds very unnatural in English. Sometimes tense is a little weird translating directly using formal polite endings. Regardless of politeness, future can be implied, although sometimes it is included anyway. 곧 합니다 sounds more sincere/immediate than 곧 할겁니다, although 곧 하겠습니다 sounds the most immediate.