Magoffin has taken 267 first-class wickets in four seasons at Sussex, although he could not prevent them from being relegated to Division Two of the Championship this year. The Australian seamer has an English wife and, after fulfilling residency criteria, is in the final stages of a passport being issued.
Taylor's arrival will add international class to Sussex's batting line-up as they seek an immediate return to Division One. Taylor, 31, averages 45.99 in Test cricket and last month made his highest score, 290 against Australia in Perth.
He is currently playing his 69th Test, against Sri Lanka in Hamilton, and has been capped a further 166 times in ODIs and in 64 T20 internationals. He will play in all three formats for Sussex from April until late July, when New Zealand are scheduled to tour Zimbabwe and South Africa.
"I am delighted to be joining Sussex in 2016," Taylor said. "I've heard nothing but positive words said about the set up at Hove and I look forward to contributing across all three forms.
"Hopefully I can play my part in helping Sussex bounce straight back from the disappointment of relegation last season. I look forward to linking up with Luke Wright, who I have been speaking to regularly, Mark Davis and my new team-mates in April."
Wright was made Sussex's captain after Ed Joyce relinquished the role at the end of the season and has been putting the contacts made during various stints in T20 competitions around the world to good use.
Only Wright and wicketkeeper Ben Brown managed to pass 1000 Championship runs in 2015 and the retirement of Michael Yardy is likely to leave a hole in the middle order. Taylor, who played T20 cricket for Durham in 2010, is Sussex's first signing since Davis was appointed head coach, following Mark Robinson's departure to take charge of England women.
"We are thrilled to have acquired the services of Ross Taylor for a large part of the 2016 season," Davis said. "He is a brilliant all-round player with high skill in all formats of the game. To have secured one of the best batsmen in world cricket is testament to the ambition that we have at Sussex Cricket Limited.
"I am sure the Taylor family will have a fantastic time with us in Hove and we look forward to establishing a great relationship with them."