The Pakistan-born twirler is currently contracted to Cricket South Africa (CSA) until 31 July, after which he will make himself available for T20 franchise cricket.
However, the 39-year-old would like to continue to don the Proteas shirt in T20 internationals ahead of the 2020 ICC Men's T20 World Cup in Australia, but believes the time is right to allow younger spin talents to emerge in the 50-over format.
Tahir qualified to play for South Africa on 1 January 2011 and was selected for the 2011 World Cup. On 15 June 2016, in a match against the West Indies, Tahir became the first South African bowler to take seven wickets in an ODI, whilst also becoming the fastest South African to reach 100 ODI wickets.
Tahir has an incredible 156 wickets at 24.56 from 95 ODIs and he is expected to be a key player for South Africa as they challenge for the ICC Cricket World Cup 2019.
“I have always wanted to play in the World Cup,” Tahir said. “It would be a great achievement for me to play for this great team. I have a mutual understanding with Cricket South Africa and going forward I decided that I would finish at the World Cup, that is why I am contracted until then.
"After that, Cricket South Africa has allowed me to go and play around the world in various leagues but I would also love to play T20 cricket for South Africa. I think I have the ability and can play a role in T20 cricket for South Africa. I am grateful for the opportunity.
“I would love to play for as long as I can, but there is a stage in your life where you have to make big decisions. This is one of those big decisions, it is definitely the biggest decision of my life.
“I also feel there are a couple of good spinners in the country who need the opportunity. We are fighting for the same spot, but looking to the future, they will have more opportunities to play for South Africa.”
Tahir took 3/26 against Sri Lanka on Sunday as South Africa claimed an eight-wicket victory in the first ODI. The second ODI takes place in Centurion on Wednesday.