Can a sponsor negotiate a shorter undertaking period in exchange for meeting a higher income requirement?

No, a sponsor cannot negotiate a shorter undertaking period in exchange for meeting a higher income requirement. The length of a sponsorship undertaking is set by regulation based on the sponsorship category, not something that's individually negotiated between the sponsor and IRCC on a case-by-case basis.

Each category of family sponsorship has its own fixed undertaking length — spousal, common-law, and conjugal partner sponsorships have a shorter length than parent and grandparent sponsorships, which run for a much longer period. Whatever category applies to your sponsorship determines the length automatically; showing a higher income than the minimum required doesn't shorten that period, and there's no formal process for requesting a trade-off between income level and undertaking length.

This sometimes surprises sponsors, particularly those sponsoring parents or grandparents, who may have significantly more income than the minimum required and assume that should count for something in terms of reducing their long-term commitment. It doesn't change the length of the undertaking itself. If you're weighing whether to sponsor a family member and want a clear picture of exactly what length of commitment applies to your situation, an immigration lawyer can walk you through what your specific category requires before you sign anything.