Excel IRR formula
Hi everyone. I need other people's view on something.
When preparing DCF models for work i always manually calculate IRR by using goal seek or manually changing the WACC. The reason I do this is because from my understanding Excel's IRR formula doesn't work properly when TV is calculated using the WACC as the circularity in the calculations causes the iterative process of the IRR formula (which is in itself just a glorified goal seek too). When using a multiple approach to calculate TV this shouldn't be an issue though.
However at my current company we usually use WACC and LTGR to calculate TV so it is indeed an issue. I first pointed this out but at nobody really believed me. In the meantime i've managed to convince my supervisor that the IRR excel formula is not accurate but everyone else in the group uses it and it is specially bad when preparing sensitivity tables for presentation as the whole thing is then not correct.
Since i am the only one who seems to see this as an issue I've come here to ask what are other people's take on this? Am i correct or am i just being stupid?