Our client was going to make a 2015 SEP contribution but wanted to wait until June 2016. He was going to file an extension for his 2015 taxes. Instead, he just realized he filed the taxes (with the SEP deduction) instead of filing the extension. He has not made a contribution to his SEP for 2015 as of now.
Can he still make the SEP contribution for 2015? Or, will he just have to file an amended tax return without the SEP deduction?

Thanks