When doing retirement planning it is important to know what your annual expenses are. I'd like to compute my expenses for 2017 but in a way that isn't tedious.

I'm thinking of doing this:

1. Get balance of all accounts on Jan 1, 2017 -> B2017
2. Get balance of all accounts on Jan 1, 2018 -> B2018
3. Get return on investments (my bank provides this) -> RETURN
4. Get income from 2017 tax return -> INCOME
5. Get income tax (and SS etc.) paid from 2017 tax return -> TAX

Compute expenses as:

INCOME - TAX - (B2018 - B2017 - RETURN)

Would that be a reasonably accurate way to compute my expenses for 2017?

When doing retirement planning it is important to know what your annual expenses are. I'd like to compute my expenses for 2017 but in a way that isn't tedious.

I'm thinking of doing this:

1. Get balance of all accounts on Jan 1, 2017 -> B2017
2. Get balance of all accounts on Jan 1, 2018 -> B2018
3. Get return on investments (my bank provides this) -> RETURN
4. Get wages/business income from 2017 tax return -> INCOME
5. Get income tax (and SS etc.) paid from 2017 tax return -> TAX

Compute expenses as:

INCOME - TAX - (B2018 - B2017 - RETURN)

Would that be a reasonably accurate way to compute my expenses for 2017?