XL 2016 Conversion langage VBA en formule excel

Bonjour,

Je ne suis pas une pro des macro, pourriez-vous svp m'aider à convertir le langage VBA en formule Excel :

1-
IF [fin] < "2021-01-01"
THEN DateTimeDiff([fin],[debut],"days")/30
ELSE DateTimeDiff("2020-12-31",[debut],"days")/30
ENDIF

IF [duree_cumul_amort]<=0
THEN 0
ELSE [duree_cumul_amort]
ENDIF

2-
IF [debut] > "2021-01-01" and [fin] < "2022-01-01"
THEN DateTimeDiff([fin],[debut],"days")/30

ELSEIF [fin] < "2022-01-01"
THEN DateTimeDiff([fin],"2021-01-01","days")/30

ELSEIF [debut] > "2021-01-01"
THEN DateTimeDiff("2021-12-31",[debut],"days")/30

ELSE DateTimeDiff("2021-12-31","2021-01-01","days")/30
ENDIF

3-
IF [debut] > "2021-01-01" and [fin] < "2022-01-01"
THEN DateTimeDiff([fin],[debut],"days")/30

ELSEIF [fin] < "2022-01-01"
THEN DateTimeDiff([fin],"2021-01-01","days")/30

ELSEIF [debut] > "2021-01-01"
THEN DateTimeDiff("2021-12-31",[debut],"days")/30

ELSE DateTimeDiff("2021-12-31","2021-01-01","days")/30
ENDIF

et

IIF([MT_TCC_FIN_INIT]-[cumul_amort_PBF]=0,0,((MT_TCC_FIN_INIT)/48)*[duree_dotation_2021])

Merci par avance pour votre aide
Cordialement