The rearranged date means that Ulster will play two home games within the space of four days.
Speaking on Monday, Ulster hooker and captain Rory Best said: "The mood in the camp remains upbeat and the players are pleased to have the fixture confirmed so they can get the training mix right.
"Our games against Munster are always massive and we are pleased now that we have the date confirmed so we can get on with preparation.
"We have four home games left and each one is vital for this season and seasons ahead.
"We know that Tuesday evening isn't a traditional Ravenhill night but we hope that our supporters will come along and recreate the infamous Ravenhill roar," he added.
With Munster playing their Heineken Cup semi-final against Saracens just two days before the game, Ulster will be hoping to score a much-needed win over the men in red, who have been in serious form of late.
Ulster Rugby Chief Executive Michael Reid said: "There were over 12,000 tickets sold initially for the game on January 4 and hopefully when supporters take into account the fact that we are playing our interprovincial rivals and with so much at stake for Ulster in terms of our position in the Magners League table, it won't matter that the game is going to be played on a Tuesday.
"It's a perfect opportunity to claim a scalp from one of the sides in contention for Heineken Cup success this season and boost our league points as well."
If you hold a ticket for this match, dated January 4, please be advised that it will now be valid for the April 29 game and will not need to be re-issued.
"The fact is that in a very congested end to the season, we will be playing and selling tickets for four home games in the space of five weeks.
In an ideal world we would have waited until now before offering refunds but we were also conscious that we'd been holding on the people's money, in some cases, since before the Christmas break and so wanted to get the process started.
"We were very up front and advised supporters that if they didn't think they would be able to make the match on either of those days then they should refund their ticket if they didn't want to potentially lose out on their money," he explained.
There are just under 1000 terrace tickets available to purchase for the re-fixed Ulster v Munster game - they will go on sale from the Ravenhill ticket office on Friday night, immediately after the Connacht match and any remaining tickets will be sold next week.
Further ticket and refund information can be found on the Ulster Rugby website or by telephoning their offices at 0044 (0)28 9049 3222.