I once calculated and came to 1497/month, then 380,000 annuity loans with special repayments of 3000 euros/year look like this:
TOTAL
380,000 repayment and special payments for about 20 years
46,232 interest for about 20 years, assuming refinancing similarly well after 15 years
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426,232 in about 20 years, with no additional taxation and uncertainties, possibly legal changes regarding Wohnriester, etc. (think of legal changes that have taken place with direct insurance). End, finished, all done.
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With 2x Riester and 180,000 annuity loans and special repayments 3000 euros/year
Total:
226,800 for 25 years x 2x 378/month
180,000 repayment and special payments for 16 years
12,283 interest for 16 years, assuming refinancing similarly well after 10 years
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419,083 total payments plus additional taxation Wohnriester etc.