Maria, anon (anonymous)

My late sister was deemed to be a Non-Resident of Canada for tax purposes because of the bilateral treaty between Germany and Canada. She passed away in December 2017 in Germany and as siblings/heirs, we are told that since, the funds are coming out of a tax sheltered plan (RRSP), the taxes: 25% as per CRA rule are due at time of withdrawal before distribution to the heirs.

Why can’t lesser taxes be applicable because of that treaty, since as a non-resident my late sister was paying taxes in all her NR4 slips, < 25% , in Germany ?

To whom should I write at CRA to clarify this matter since my communications with them have been unidirectional thus far ?

Thank you in anticipation